Objective Worldwide helplines are considered an important part of suicide prevention strategies. Nevertheless, evidence regarding the impact of suicide prevention helplines on the suicidality of its users remains limited and is frequently confronted with methodological issues. This study aimed to assess the impact of crisis calls on callers’ levels of crisis and suicidality both immediately after the call and at follow-up compared to before the call. After the call, the satisfaction of the callers with the intervention was also assessed. Methods A pre-post study, generated automatically by a telephone system, was conducted in order to compare the level of crisis and suicidality (operationalized by five indicators: hopelessness, entrapment, controllability, suicidal intent, and social support) experienced by callers before and immediately after the call and at follow-up (one to two weeks after the call). Results Callers (n = 487) showed significant improvement in their level of crisis (p < .001, d = −0.31), hopelessness (p < .001, d = −0.22), entrapment (p < .001, d = −0.25), suicide intent (p < .001, d = −0.37), and social support (p < .001, d = 0.33) after the call compared to before the call. Improvements were also found at follow-up compared to pretest. The satisfaction of callers with the helpline was high. Conclusions This study adds to the growing evidence on suicide prevention helplines and addresses some important methodological issues in helpline research. Furthermore, it shows promising results regarding the potential supportive impact of helplines on callers who feel suicidal.