Note-taking has been largely studied in contexts of work meetings. However, often people need to remember information exchanged in informal situations, such as during mobile phone conversations. In this paper we present a study conducted with 59 subjects who had their phone calls semi-automatically transcribed for later annotation. Analysis of the 621 calls and the subjects' annotation behavior revealed that phone recall is indeed a relevant user need. Furthermore, identifying patterns in phone calls such as numbers and names provide better indicators of annotation than variables related to the callers' profile, context of calls, or quality of service. Our findings suggest implications for the design of mobile phone annotation tools.