Conventional Telephone Research Articles

LO084: Text messaging research participants as a follow-up strategy to decrease emergency department study attrition

Introduction: Collecting patient-reported follow-up data for prospective studies in the emergency department (ED) is challenging in this acute care, minimal continuity setting. Follow-up is frequently attempted using telephone contact and in some instances mail correspondence. The objective of this study was to determine if text messaging study participants involved in an ongoing randomized trial resulted in a lower rate of attrition as compared to conventional telephone follow-up. Methods: This was a secondary analysis of research participants enrolled in a randomized controlled trial assessing head injury discharge instructions. Adult (18-64 years) patients presenting to an academic ED (annual census 65,000) with chief complaint ‘head injury’ occurring within 24 hours of ED visit were contacted by telephone 2 and 4 weeks post ED visit to complete a symptom questionnaire. During the first 4 months of study follow-up, participants were contacted by a conventional telephone call. Attrition was higher than anticipated, thus we received subsequent ethics approval for the final 3 months of follow-up duration to contact participants by text message on the day of the first telephone attempt as a reminder of the telephone interview scheduled later that day. The proportion of patients lost to follow-up at 2 and 4 weeks post ED visit was compared between participants not receiving and receiving reminder text messages. Results: 118 patients were enrolled in the study (78 underwent conventional follow-up and 40 received text messages). Mean (SD) age was 35.2 (13.7) years and 43 (36.4%) were male. During the period of conventional follow-up, 3 participants withdrew from the study. Of the remaining 75 participants, 24 (32.0%) at 2 weeks and 32 (42.7%) at 4 weeks were unable to be contacted. Of the 40 participants receiving a reminder text message, 4 (10.0%) at 2 weeks and 10 (25.0%) at 4 weeks were unable to be contacted. Overall, text messaging study participants decreased attrition by 22% (95% CI: 5.9%, 34.7%) and 17.7% (95% CI: -0.8%, 33.3%) at 2 and 4 week follow-up, respectively. Conclusion: In this young ED cohort participating in a randomized trial, text message reminders of upcoming telephone follow-up interviews decreased the rate of attrition. Text messaging is a viable, low-cost communication strategy that can improve follow-up participation in prospective research studies.

A Development of Trusted Mobile Smart Message Wallet Service Broker (TmSMWSB) Architecture

The rapid advances made in the information and communication technologies have kindled and fueled a fast-paced and widespread shift of information exchange and communication channels between businesses and customers from conventional post and telephone services to mobile-based online services and smartphones. Along with the growing number of smartphone users, an increasing number of people fall victim to new types of financial crimes committed with fraudulent electronic means, such as smishing, pharming, phishing, app/web forgery and fraud, pretending to be a corporate. In this paper, we propose a reliable broker service process providing a communication channel between companies and customers based on the Mobile Wallet (app) on smartphones. The salient features of its process design and implementation are prescreening out fraudulent information and providing customers Smart Wallet-based safe information and services.

Spectral shifting of speaker‐specific information for narrow band telephonic speaker recognition

Speech-based authentication system can perform remote authentication over telephone channels. However, telephone channels are restricted to a bandwidth of ∼0–4 kHz while studies on the distribution of speaker-specific information in the speech spectrum strongly suggests that useful speaker-specific information is present above 4 kHz. A method to shift a part of this speaker-specific information above 4 kHz into the telephone bandwidth in place of less speaker-specific information originally present below 4 kHz is proposed. Speaker recognition experiments conducted using the proposed method leads to ∼18.5% relative improvement on equal error rate when compared to a system using the conventional telephone band speech, as evaluated on the Intelligence Advanced Research Projects Activity (IARPA) Babel Program Tamil language collection.

The effect of the combination of video feedback and telephone intervention on postdischarge rehabilitation in patients receiving artificial total hip replacement

Objective To explore the effect of the combination of video feedback and telephone intervention on postdischarge rehabilitation in patients receiving artificial total hip replacement. Methods A total of 60 patients receiving artificial total hip replacement were divided into intervention group and control group with 30 cases each by random digits table method. The combination of video feedback and telephone intervention was conducted in intervention group, and conventional discharge guidance and telephone follow-up on a regular basis in control group. In intervention group, the patients or their family member were asked to record the video of the exercises and daily living when patients were at home according instructions and researchers assessed the condition of patient's joint and muscle function and provided individual education and instructions to the patients on the basis of the feedback video through telephone. Harris hip function rating scale and Functional Independence Measure (FIM) were investigated at discharge and 1, 3, 6 months after discharge. Results There were no significant differences in Harris hip function rating scale and FIM score at discharge between 2 groups, P>0.05. Harris hip function rating scale score were (72.70± 11.65), (83.11±5.12), (94.83±3.08) scores at 1, 3, 6 months after discharge in intervention group, and (63.20±14.96), (77.00±11.62), (87.50±7.94) scores in control group, there were significant differences, P< 0.05 or <0.01. FIM score were (96.30±4.63), (108.76±3.28), (125.79±1.19) scores at 1, 3, 6 months after discharge in intervention group, and (78.23±5.09), (86.43±6.30), (96.54±5.35) scores in control group, there were significant differences, P<0.01. Conclusion The combination of video feedback and telephone intervention could help to promote the postdischarge hip function for patients receiving artificial total hip replacement. Key words: Arthroplasty, replacement, hip; Rehabilitation; Video recording; Multimedia

Does Robotic Telerounding Enhance Nurse-Physician Collaboration Satisfaction About Care Decisions?

Delivering healthcare using remote robotic telepresence is an evolving practice in medical and surgical intensive critical care units and will likely have varied implications for work practices and working relationships in intensive care units. Our study assessed the nurse-physician collaboration satisfaction about care decisions from surgical intensive critical care nurses during remote robotic telepresence night rounds in comparison with conventional telephone night rounds. This study used a randomized trial to test whether robotic telerounding enhances the nurse-physician collaboration satisfaction about care decisions. A physician randomly used either the conventional telephone or the RP-7 robot (InTouch(®) Health, Santa Barbara, CA) to perform nighttime rounding in a surgical intensive care unit. The Collaboration and Satisfaction About Care Decisions (CSACD) survey instrument was used to measure the nurse-physician collaboration. The CSACD scores were compared using the signed-rank test with a significant p value of ≤0.05. From December 1, 2011 to December 13, 2012, 20 off-shift nurses submitted 106 surveys during telephone rounds and 108 surveys during robot rounds. The median score of surveys during robot rounds was slightly but not significantly higher than telephone rounds (51.3 versus 50.5; p=0.3). However, the CSACD score was significantly increased from baseline with robot rounds (51.3 versus 43.0; p=0.01), in comparison with telephone rounds (50.5 versus 43.0; p=0.09). The mediators, including age, working experience, and robot acceptance, were not significantly (p>0.1) correlated with the CSACD score difference (robot versus telephone). Robot rounding in the intensive care unit was comparable but not superior to the telephone in regard to the nurse-physician collaboration and satisfaction about care decision. The working experience and technology acceptance of intensive care nurses did not contribute to the preference of night shift rounding method from the aspect of collaboration with the physician about care decision-making.

Unsupervised Clustering-based SPITters Detection Scheme

VoIP /SIP is taking place of conventional telephony because of very low call charge but it is also attractive for SPITters who advertise or spread phishing calls toward many callees. Although there exist many feature-based SPIT detection methods, none of them provides the flexibility against multiple features and thus complex threshold settings and training phases cannot be avoided. In this paper, we propose an unsupervised and threshold-free SPITters detection scheme based on a clustering algorithm. Our scheme does not use multiple features directly to trap SPITters but uses them to find the dissimilarity among each caller pair and tries to separate the callers into a SPITters cluster and a legitimate one based on the dissimilarity. By computer simulation, we show that the combination of Random Forests dissimilarity and PAM clustering brings the best classification accuracy and our scheme works well when the SPITters account for more than 20% of the entire caller.

Adaptation of cochlear implant fitting to various telecommunication systems: a proposal for a ‘telephone map'

Conclusions: Despite the innovations in cochlear implant (CI) technology in recent years, some auditory tasks remain difficult for CI recipients. This work proposes the creation of specific maps for telephone communication (via conventional phone and via Internet protocol, VoIP). In light of our preliminary results, we believe that our experimental maps might improve conventional telephone and Internet communications for CI recipients. Objectives: This study aimed to: (1) analyze the spectro-temporal characteristics of the signals; (2) evaluate speech recognition scores using two different types of telephone communication; and (3) change some map parameters on the basis of the previous signal analysis, to obtain a specific map for telephone use. Methods: Eleven Cochlear™ Nucleus® CI recipients were tested for bisyllabic word recognition in quiet using reproduced voice and transmitted voice via conventional telephone and Skype® using the habitual-ACE (SLB) map, and two experimental maps (F- and V-Map). Results: The results showed a worsening of word recognition scores with SLB-Map via telephone (30.5%) and VoIP (18.6%) compared with those achieved with the same map in an anechoic booth. In the experimental listening conditions, 65% and 54% of patients performed better with F- and V-Map, respectively, up to a maximum of performance improvement by 35% via telephone and 25% via VoIP.

Development of Indicators for Information Security Level Assessment of VoIP Service Providers

VoIP (Voice over Internet Protocol) is a technology of transmitting and receiving voice and data over the Internet network. As the telecommunication industry is moving toward All-IP environment with growth of broadband Internet, the technology is becoming more important. Although the early VoIP services failed to gain popularity because of problems such as low QoS (Quality of Service) and inability to receive calls as the phone number could not be assigned, they are currently established as the alternative service to the conventional wired telephone due to low costs and active marketing by carriers. However, VoIP is vulnerable to eavesdropping and DDoS (Distributed Denial of Service) attack due to its nature of using the Internet. To counter the VoIP security threats efficiently, it is necessary to develop the criterion or the model for estimating the information security level of VoIP service providers. In this study, we developed reasonable security indicators through questionnaire study and statistical approach. To achieve this, we made use of 50 items from VoIP security checklists and verified the suitability and validity of the assessed items through Multiple Regression Analysis (MRA) using SPSS 18.0. As a result, we drew 23 indicators and calculate the weight of each indicators using Analytic Hierarchy Process (AHP). The proposed indicators in this study will provide feasible and reliable data to the individual and enterprise VoIP users as well as the reference data for VoIP service providers to establish the information security policy.

Can Smartphones Enhance Telephone-Based Cognitive Assessment (TBCA)?

TBCA has emerged to solve the limitations of administering cognitive assessments face-to-face. The recent development of telephones and knowledge advances in the area of cognitive impairment may affect the development of TBCA. The purpose of this paper is to discuss how smartphones can be used to enhance the applicability of TBCA, which has previously been administered by conventional telephone. This paper will first review, describe and critique the existing TBCA instruments. It will then discuss the recent developments in tele-technology, the popularity of tele-technology among the elderly, potential benefits and challenges in using smartphones for cognitive assessment, and possible future developments in this technology. In the systematic review, eighteen TBCA instruments were identified. They were found to be valid in differentiating between people with and without dementia. TBCA was previously found to be launched on a conventional telephone platform. The advances in understanding of cognitive impairment may demand that telephones be equipped with more advanced features. Recently, the development and penetration of smartphones among the elderly has been rapid. This may allow the smartphone to enhance its TBCA applicability by overcoming the limitations of the conventional telephone, rendering the TBCA more efficient in addressing the increasing demand and complexity of cognitive assessments in the future. However, more research and technology developments are needed before smartphones can become a valid platform for TBCA.

The effect of psychosocial interventions delivered by telephone and videophone on quality of life in early-stage breast cancer survivors and their supportive partners

Summary We examined the effectiveness of two psychosocial interventions for improving QOL in recently diagnosed breast cancer survivors and their partners. The interventions were telephone health education (THE) and interpersonal counselling. The latter was delivered by telephone (TC) or by videophone (VC) in 8 weekly one-to-one sessions. Fifty two dyads composed of a woman with breast cancer and her supportive partner were randomly assigned to THE, TC or VC. The average age of the survivors was 53 years (range 40–66), and they were mainly white, married, with a college education, and employed. Approximately half of the supportive partners were spouses. Surveys of quality of life (QOL) were made at three points in the study, each separated by 8 weeks. There was significantly higher attrition in the THE group compared to the videophone or telephone counselling groups among both survivors (44% vs. 10% and 8%) and partners (44% vs. 10% and 15%). Regardless of group, participants showed increased QOL over time. Survivors’ and partners’ social well-being improved in the telephone and videophone interpersonal counselling treatment groups, but not in the health education group. Telephone-delivered psychosocial interventions can be effective for managing QOL in breast cancer survivors and their supportive partners. There was no evidence of superior outcomes associated with using videophones over the conventional telephone.

On the Importance of Public Opinion

© 2012 by the American Academy of Arts & Sciences LEE EPSTEIN, a Fellow of the American Academy since 2006, is the Provost Professor of Law & Political Science and the Rader Family Trustee Chair in Law at the University of Southern California. She is the author, coauthor, or editor of 1⁄2fteen books, including Constitutional Law for a Changing America, 7th ed. (with Thomas G. Walker, 2011) and Advice and Consent: The Politics of Judicial Appointments (with Jeffrey A. Segal, 2005). Her current book project, The Behavior of Federal Judges: A Theoretical and Empirical Study of Rational Choice (with William M. Landes and Richard A. Posner), will be published in late 2012. “The president’s job approval rating is up”; “50 percent of Americans believe that their taxes will increase in the next year”; “The incumbent senator is the projected winner by a 2-1 margin.” This is how most of us follow and understand public opinion: through survey and election results that seem to be everywhere. But there is much more to public opinion than a percentage or an outcome reported in a headline, posted on a website, or tweeted, emailed, or texted. The authors in this issue speak to the “much more.” How do we learn about public opinion, and what does it tell us? These are the questions considered in our 1⁄2rst four essays. D. James Greiner and Kevin Quinn begin the volume with a fascinating glimpse into the world of polling, especially exit polls. Greiner, an expert on voting rights, and Quinn, a political scientist with expertise in statistical methodology, are uniquely poised commentators. The two have conducted exit polls of their own–but that may be damning with faint praise. After the debacle in Florida with the 2000 presidential election, many of us are skeptical of exit polls. Greiner and Quinn share our skepticism, suggesting that exit polls “are most prone to fail when we most want them to work”–that is, in close elections. But this is not their only concern. In a day and age when conventional (telephone) and more au courant (Internet) polling techniques can provide vast amounts of information far more cheaply, Greiner and Quinn question whether exit polls will and should survive.

Speech Perception Benefits of Internet Versus Conventional Telephony for Hearing-Impaired Individuals

BackgroundTelephone communication is a challenge for many hearing-impaired individuals. One important technical reason for this difficulty is the restricted frequency range (0.3–3.4 kHz) of conventional landline telephones. Internet telephony (voice over Internet protocol [VoIP]) is transmitted with a larger frequency range (0.1–8 kHz) and therefore includes more frequencies relevant to speech perception. According to a recently published, laboratory-based study, the theoretical advantage of ideal VoIP conditions over conventional telephone quality has translated into improved speech perception by hearing-impaired individuals. However, the speech perception benefits of nonideal VoIP network conditions, which may occur in daily life, have not been explored. VoIP use cannot be recommended to hearing-impaired individuals before its potential under more realistic conditions has been examined.ObjectiveTo compare realistic VoIP network conditions, under which digital data packets may be lost, with ideal conventional telephone quality with respect to their impact on speech perception by hearing-impaired individuals.MethodsWe assessed speech perception using standardized test material presented under simulated VoIP conditions with increasing digital data packet loss (from 0% to 20%) and compared with simulated ideal conventional telephone quality. We monaurally tested 10 adult users of cochlear implants, 10 adult users of hearing aids, and 10 normal-hearing adults in the free sound field, both in quiet and with background noise.ResultsAcross all participant groups, mean speech perception scores using VoIP with 0%, 5%, and 10% packet loss were 15.2% (range 0%–53%), 10.6% (4%–46%), and 8.8% (7%–33%) higher, respectively, than with ideal conventional telephone quality. Speech perception did not differ between VoIP with 20% packet loss and conventional telephone quality. The maximum benefits were observed under ideal VoIP conditions without packet loss and were 36% (P = .001) for cochlear implant users, 18% (P = .002) for hearing aid users, and 53% (P = .001) for normal-hearing adults. With a packet loss of 10%, the maximum benefits were 30% (P = .002) for cochlear implant users, 6% (P = .38) for hearing aid users, and 33% (P = .002) for normal-hearing adults.ConclusionsVoIP offers a speech perception benefit over conventional telephone quality, even when mild or moderate packet loss scenarios are created in the laboratory. VoIP, therefore, has the potential to significantly improve telecommunication abilities for the large community of hearing-impaired individuals.

Rat testicular impairment induced by electromagnetic radiation from a conventional cellular telephone and the protective effects of the antioxidants vitamins C and E

OBJECTIVE:The aim of this study was to investigate the possible effects of electromagnetic radiation from conventional cellular phone use on the oxidant and antioxidant status in rat blood and testicular tissue and determine the possible protective role of vitamins C and E in preventing the detrimental effects of electromagnetic radiation on the testes.MATERIALS AND METHODS:The treatment groups were exposed to an electromagnetic field, electromagnetic field plus vitamin C (40 mg/kg/day) or electromagnetic field plus vitamin E (2.7 mg/kg/day). All groups were exposed to the same electromagnetic frequency for 15, 30, and 60 min daily for two weeks.RESULTS:There was a significant increase in the diameter of the seminiferous tubules with a disorganized seminiferous tubule sperm cycle interruption in the electromagnetism-exposed group. The serum and testicular tissue conjugated diene, lipid hydroperoxide, and catalase activities increased 3-fold, whereas the total serum and testicular tissue glutathione and glutathione peroxidase levels decreased 3-5 fold in the electromagnetism-exposed animals.CONCLUSION:Our results indicate that the adverse effect of the generated electromagnetic frequency had a negative impact on testicular architecture and enzymatic activity. This finding also indicated the possible role of vitamins C and E in mitigating the oxidative stress imposed on the testes and restoring normality to the testes.

Remote care by telemedicine in the ICU

Telemedicine, by the use of audiovisual technologies, is increasingly being used to assist in patient care by ICUs unable to be staffed by consultant intensivists. This review discusses the recent evaluation of these services and their potential role in managing intensive care patients. Models of care range from complete remote 24 h surveillance requiring direct video observation to a consultation liaison service only requiring conventional telephone links. There has been a rapid adoption of such services especially in North America where access to on-site intensive care specialists is limited for the volume of intensive care being undertaken. Early work suggests savings in terms of cost and length of stay with an improvement in compliance with care protocols. However, later work is not as supportive of such services, possibly related to differing care infrastructures and the organization of individual units. The key task is to ascertain the most appropriate service requirements that would assist in care for a given patient circumstance. Clear benefits of ICU-telemedicine systems remain unclear but at least the systems appear safe. Formal reviews of the impacts and contribution of ICU telemedicine to processes of care, the effects on unit staffing, hospital organization, and the healthcare region are needed. However, ICU-telemedicine is available and being embraced by some, especially to deal with the tyranny of distance.

Performance Evaluation of QoS parameters in UMTS Network Using Qualnet

A UMTS network based on the Wide Band-CDMA technology is a 3 rd generation tele- communication system which provides various multimedia applications along with the conventional telephony service. These various multimedia applications fall into four different categories, which are differentiated from each other on the basis of required bit rate and delay tolerance etc. parameters. In order to get best Quality of Service (QoS) for a particular application running on the subscriber equipment the parameters of the respective category to which the application belong need to be in a required range. In this work the performance of a UMTS network scenario is evaluated by using various values of the precedence bits of the CBR application. The simulation tool used is QUALNET 5.0. The performance of the scenario according to the respective precedence bits is analyzed by four metrics: average jitter, end to end delay, throughput and UMTS signals received and forwarded to MAC. The comparative analysis of all the four metrics according to the precedence bit values will be carried out and it will be concluded in the last section that which precedence bit gives the best performance for the simulated UMTS network scenario.

Quality-adjusted life years gained in patients aged over 65 years after total hip replacement

Summary Background Total hip replacement (THR) is an effective, but cost-intensive health care procedure for older people. Because of demographic changes in Western Europe, THR-associated financial investment in health care has become a priority. To provide a quantitative rationale for a discussion within Western European health care systems, we undertook a prospective assessment of the benefit of an additional intervention following THR from the patients´ perspective and as measured by quality-adjusted life years (QALYs). Aim To measure the difference in health-related quality of life between an intervention (telephone support) and control group preoperatively and at follow-up 9months after THR. Methods A randomised clinical trial was conducted which allocated 180 patients aged over 65years to either an intervention group or a control group. The control group received conventional treatment and the intervention group received both conventional treatment and telephone support after discharge. QALYs were calculated from measures of health-related quality of life using the SF-36 questionnaire. These scores were transformed to QALYs using a formula based on the method developed by Brazier et al. (1998). Results Both the control and the intervention patients reported significant changes in health status from preoperative status at 3 and 9months after surgery. Both groups group had a gain in QALYs. Interpretation There was a significant gain in health status in both groups. However, no significant or clinically relevant differences between the two groups were observed at follow-up within this timeframe.

How Internet Telephony Could Improve Communication for Hearing-Impaired Individuals

To test, whether modern Internet telephony with a broadband transmission (0.1-8 kHz) of speech improves speech perception in comparison to conventional telephony (0.3-3.5 kHz) in hearing-impaired and normal-hearing adults. Experimental clinical study. Audiologic laboratory in a tertiary referral center in Bern, Switzerland. Twenty-one adult hearing-impaired patients consisting of 11 users of cochlear implants and 10 users of hearing aids were selected from the institution's database based on pure tone audiograms, speech perception scores, and device settings. Ten normal-hearing adults served as controls. Superiority trial of speech perception assessed with Internet versus conventional telephone quality and noninferiority trial of Internet telephone versus frequency restricted, uncompressed audio CD quality. A modern broadband codec was chosen to simulate Internet telephone quality, and ideal network conditions without packet loss were assumed. Speech perception scores of a monosyllabic word test in quiet and a sentence test in background noise assessed in different audio qualities. : Test scores were, on average, 15% (4-33) higher in the monosyllabic word and 25% (8-51) higher in the sentence test using Internet versus conventional telephone quality across all subject groups. Speech perception was not significantly different when Internet telephone quality was compared with high-cut CD quality. Internet telephony offers significantly improved speech perception to hearing-impaired and normal-hearing adults under ideal laboratory conditions through doubling the frequency range and through conserving audio quality during digital sound processing.

Replacing Conventional Telephones by VoIP: Their Major Constraints &amp; Solutions

Replacing Conventional Telephones by VoIP: Their Major Constraints &amp; Solutions

Feasibility and safety of remote radiology interpretation with telephone consultation for acute stroke in Thailand

"Telestroke" is emerging as a potential timesaving, efficient means for evaluating patients experiencing acute ischemic stroke. It provides an opportunity for administration of thrombolytic drugs within the short therapeutic time window associated with AIS. We describe our experiences of the feasibility and safety of remote radiology interpretation with telephone consultation. Thammasat Stroke Center employs a computed tomography-digital imaging and communication in medicine (CT-DICOM) image transfer by PACS (SYNAPSE-Fujifilm), providing a real-time CT image transferred directly to the stroke consultants. The patient data are communicated by traditional telephone conversation. Here, we assessed patients who received intravenous rt-PA treatment for ASI between October 2007 and January 2009. A total of 458 patients with AIS and transient ischemic attack (TIA) were admitted to a stroke unit during the study period. One hundred patients received intravenous rt-PA (21%). Median NIHSS before thrombolysis was 15 (3-34). Mean door-to-needle time was 54 minutes (15-125). Mean onset-to-treatment time OTT was 160 minutes (60-270). There were 13 asymptomatic intracerebral hemorrhages and two (one fatal) symptomatic intracerebral hemorrhages. At 3 months, 42 patients had achieved excellent recovery (mRS, 0-1) and 14 had died. Administration of rt-PA for AIS with remote radiology interpretation with telephone consultation was feasible and safe, and the system was well received. Further studies are needed to determine the benefit of this method as compared to the conventional telephone consultation alone.

A stochastic fluid model for an ad hoc mobile network

In conventional mobile telephone networks, users communicate directly with a base station, via which their call is transferred to the recipient. In an ad hoc mobile network, there is no base-station infrastructure and users need to communicate between themselves, either directly if they are close enough, or via transit nodes if they are not. A number of interesting questions immediately arise in the modeling of ad hoc mobile networks. One that has received attention in the literature concerns how to encourage users to act as transit nodes for calls that they are not partaking in. Solutions to this problem have involved each user maintaining a `credit balance' which is increased by forwarding transit calls and decreased by transmitting one's own calls. A second question concerns the `amount of resource' that a network needs in order to be able to operate with a reasonable quality of service. We shall consider this question by modeling each user's battery energy and credit balance as fluids, the rate of increase or decrease of which is modulated by the network occupancy. This results in a network of stochastic fluid models, each modulated by the same background process. In this paper, we shall assume that there is no bound on the energy or the credit that a user's handset can accumulate. Using this model, we can calculate the critical rates of recharge that are necessary and sufficient to guarantee that no calls are lost. For recharge rates less than the critical values, we propose a reduced-load approach to the analysis of the network.