An Internet protocol (IP) telephony system provides telephony services to a mobile telephony device via data packet communications that traverse a data network. If the IP telephony system has received calls that were missed by the user of the mobile telephony device, or if the IP telephony system has received communications that have not yet been reviewed by the user of the mobile telephony device, information about those missed calls and unreviewed messages is delivered to the mobile telephony device so that the user can be alerted to their existence. The information may be delivered to the mobile telephony device in a push notification.