[asterisk-users] T38 negotiation, the last step !

[Klaus Darilion]

Xavier Cardil schrieb:
> Hi, I've managed to get HYLAFAX---->T38MODEM----->
> ASTERISK---->CISCOAS5400 working, but when they are negotiating asterisk 
> drops a message telling "Unknown RTP codec 96 received from gateway" Do 
> somebody know how to fix it ? 
> 
> Thank you !
> 
> 
> 
> << [ TYPE: Control (4) SUBCLASS: Ringing (3) ] [SIP/GWCISCO5400O-600bfcc8]
> << [ TYPE: Control (4) SUBCLASS: Answer (4) ] [SIP/GWCISCO5400O-600bfcc8]
> << [ TYPE: Null Frame (5) SUBCLASS: N/A (0) ] [SIP/GWCISCO5400O-600bfcc8]
> << [ TYPE: Null Frame (5) SUBCLASS: N/A (0) ] [SIP/GWCISCO5400O-600bfcc8]
> << [ TYPE: Control (4) SUBCLASS: T38/Negotiation Requested (19) ] 
> [SIP/GWCISCO5400O-600bfcc8]
> << [ TYPE: Null Frame (5) SUBCLASS: N/A (0) ] [SIP/GWCISCO5400O-600bfcc8]
> [Jul 16 17:50:39] NOTICE[2736]: rtp.c:1739 ast_rtp_read: Unknown RTP 
> codec 96 received from '192.168.3.163'

Is '192.168.3.163' the Cisco GW? If yes, then it is probably an NSE 
packet. NSE is a Cisco proprietary FaxoverIP solution and uses per 
default payload types 96 and 97 to signal a changeover from VoIP to FoIP.

Probably you have to configure the Cisco GW to use T.38 instead of NSE 
for FoIP.

regards
klaus