== MGCP Extensions The MGCP protocol is extendable. The following non-standard extensions are understood by OsmoMGW. === `X-Osmo-IGN` `X-Osmo-IGN` indicates to OsmoMGW that specific items of an endpoint should be ignored, so that it is lenient on mismatching values that would normally indicate collisions or configuration errors. ==== `X-Osmo-IGN` Format The value part of `X-Osmo-IGN` must be one or more items separated by one or more spaces. Each item consists of one or more non-whitespace characters. .Example: `X-Osmo-IGN` format with three ficticious items "X", "abc" and "123". ---- X-Osmo-IGN: X abc 123 ---- `X-Osmo-IGN` must be issued in the MGCP header section (typically as its last item), before the SDP section starts. ==== Supported `X-Osmo-IGN` Items Currently, the following `X-Osmo-IGN` items are supported: * `C`: ignore CallID mismatches, i.e. differing "C" values between connections on the same endpoint. .Note: `X-Osmo-IGN` does not support ignoring mismatches on the domain part of an endpoint name, e.g. ignoring a mismatch on "example.com" in `rtpbridge/123abc@example.com`. Instead, you may globally configure OsmoMGW with `mgcp` / `domain *` to permit all domain parts. ===== `X-Osmo-IGN: C` By default, OsmoMGW verifies that all CallIDs ("C" values) match for all connections on any one given endpoint. To ignore CallID mismatches, pass a `C` in the `X-Osmo-IGN` header, for the first or the second `CRCX` on an endpoint. When the `X-Osmo-IGN: C` is sent for any one `CRCX` on an endpoint, CallID mismatches will be ignored for that and all subsequent messages for that endpoint. Hence this header only needs to be included once per endpoint, in any `CRCX` message that precedes or coincides with a CallID mismatch. This is particularly useful for a BSC that is connected to an A/SCCPlite MSC, where the BSC and MSC each are expected to configure their respective own connection on a shared endpoint. For A/SCCPlite, it is impossible for the BSC to know the CallID that the MSC will use, so CallID mismatches are inevitable. See also OsmoBSC, which will by default pass the `X-Osmo-IGN: C` header for endpoints associated with an A/SCCPlite MSC. .Example: `CRCX` message that instructs OsmoMGW to ignore CallID mismatches ---- CRCX 2 rtpbridge/123abc@mgw MGCP 1.0 M: recvonly C: 2 L: p:20 X-Osmo-IGN: C v=0 c=IN IP4 123.12.12.123 m=audio 5904 RTP/AVP 97 a=rtpmap:97 GSM-EFR/8000 a=ptime:40 ---- === `X-Osmux` See <>