In one embodiment, a first computing device communicating with a second computing device through a communications channel transmits an out-of-band message indicative of the urgency of the communication through a notification channel. In particular embodiments, a server acts as a proxy for relaying the out-of-band message from the first device to the second device. The second device calculates an implicit urgency score based on the communication characteristics, and combines the implicit score with the explicit urgency indicator to determine whether a call is urgent. In particular embodiments, communication handling may be affected by the determination of urgency.