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Cisco Bug: CSCuq22701 - T-38 fails when CM sends multiple re-Invites to fax server

Last Modified

Apr 16, 2018

Products (1)

  • Cisco Unified Communications Manager (CallManager)

Known Affected Releases

10.5(1.10000.7) 10.5(2.10000.5) 11.0(0.98000.299)

Description (partial)

SIP to SIP fax call with MTP fails. Re-invite after switch over to T.38 is sent from the CM using a CM IP address and fake port and SDP mode being set as sendrecv.

Fax is initiated by the fax server, after the call switches to fax CM sends an initial re-Invite to the other fax server to make sure it supports fax using CM's IP address and a fake port with SDP mode set to sendrecv. This causes the fax server to try to establish the connection using the fake port and to ignore the second re-Invite with the actual port.
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