The purpose of this study was1) to study the situationof customers using mobile phone network services of Lao Telecommunications Company, 2) to studythe significantbetween customers andthe mobile network of Lao Telecommunications Company, 3) to findout the factors affecting customer's loyalty to the mobile phone network service of Lao Telecommunication Public Company.It was a quantitative research with the target group being customers who use the service through the mobile phone network of customers of Lao Telecommunications Company in Uodomxay province, used402 sample group and questionnaires were usedto collect data and analyzedthe data by usingSPSS program. The results found that most of the users of the Lao Telephony network service wereusing the Internet (Data), spending 50,000-100,000 kip per month, the period of using the number is more than 2 years. The important aspects in makinga relationship with Lao Telecom customers are marketing promotion, service process, customer monitoring, administration, communication between customers, and partnership which are in the high level. Factors affecting customers' loyalty to Lao Telecommunication Public Company's mobile network services include repeat service use factors, referral factors, and non-switching network factors with a statistical significancelevel of 0.01