# MSPP endpoint filters

Each MSPP endpoint consists of a single MSPP filter. The MSPP service provides the following set of endpoints for sending and receiving data over a network interface:

Endpoint type | Description
DS0 (PSTN) | Entry and exit point for simplex or full duplex PSTN data.
RTP IPv4 full duplex | Entry and exit point for full duplex voice over IPv4 data streams (includes an RTP header within UDP packets).
RTP IPv4 simplex receive | Entry point for simplex voice over IPv4 data streams (includes an RTP header within UDP packets).
RTP IPv4 simplex send | Exit point for simplex voice over IPv4 data streams (includes an RTP header within UDP packets).
RTP IPv6 full duplex | Entry and exit point for simplex voice over IPv6 data streams (includes an RTP header within UDP packets).
RTP IPv6 simplex receive | Entry point for simplex voice over IPv6 data streams (includes an RTP header within UDP packets).
RTP IPv6 simplex send | Exit point for simplex voice over IPv6 data streams (includes an RTP header within UDP packets).
T38UDP | Entry and exit point for full duplex T.38 fax over UDP data streams (IPv6 not supported).
TPKT | Entry and exit point for full duplex voice data stream multiplexed according to the ThroughPacket algorithm (IPv6 not supported).

The following illustration shows a typical MSPP RTP endpoint. A single RTP full duplex endpoint filter performs all the tasks required to send and receive voice data over the IP interface.