A handheld electronic device includes one or more networking applications that enables the handheld electronic devices to be used as a networking device. The networking application monitors the types of contact that the user has with individuals, the frequency of contact, and type of contact, to infer the closeness of the relationships between the user and the contact. The networking application may monitor not only network based contact, but also physical contact between the two individuals. Knowledge of the closeness level may enable the handheld electronic device to classify contacts, so that different contacts may be handled differently by the handheld electronic device. The closeness level may also be used to alert the user to the presence of people that are close contacts. An anonymizing service may be provided to enable communications between people without requiring them to exchange sensitive personal information until the closeness level reaches a particular threshold.