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Cisco Bug: CSCsz33517 - MGCP failed to negotiate iLBC, 401 response for MDCX with sendrecv

Last Modified

Jan 30, 2017

Products (1)

  • Cisco AS5400 Series Universal Gateways

Known Affected Releases


Description (partial)

Cannot make successful calls when calling from PSTN to SIP (and vice versa) using iLBC. Calls just ring but when answered they dropped. 

Platform: AS5400XM with c5400-is-mz.124-20.T2.
Topology: PSTN---SS7---PGW--- SIP. Note: The AS5400XM is being used as an ITP-L.

Behavior observed: When trying to establish the media path, we observed that after receiving 200 OK from the SIP side, PGW instructs the GW to change the connection to "sendrecv", but GW rejects the call with 401 "Call Setup Failed".
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