Some further reading on Default Dial Peer 0:
Key points for the exam are around capabilities and features if you match this dialpeer, which I believe should be never! 😉
Dial-peer 0 (pid:0) has a default configuration that cannot be changed. The default dial-peer 0 fails to negotiate non-default capabilities, services, and applications such as:
- Non-default Voice-Network capabilities: dtmf-relay, no vad, and so forth.
- Direct Inward Dial (DID)
- TCL Applications
Dial-peer 0 for inbound VoIP peers has this configuration:
- any codec
- vad enabled
- no rsvp support
- fax-rate voice
Note: The default DSCP for voice is EF codepoint 101110 (RFC 2598), and the default DSCP for signaling is AF31 codepoint 011010 (RFC 2597). The default dial peer does not mark packets to DSCP 0. All voice packets on the routers are marked by default (this can be overridden by the dial peer), signaling with AF31 and media with EF. Calls that match the default dial peer 0 should also have this behavior.
Dial-peer 0 (pid:0) for inbound POTS peers has this configuration:
- no ivr application