# Overview of unsolicited events

The MSPP service returns a series of unsolicited events that enable applications to monitor the following:

- Route availability of RTP and UDP sessions associated with RTP (IPv4 and IPv6), T38UDP, or TPKT endpoints.

- RTCP reports associated with RTP sessions.

- Inband DTMF carriage status (in accordance with RFC 2833).

- T.38 fax session billing information (described in Receiving fax billing events).

Route availability events are returned automatically if the active data path from an RTP or UDP endpoint is interrupted and then again when the path is reestablished. RTCP and T.38 session unsolicited events are associated with particular types of MSPP channels and must be explicitly enabled by the application.