07-06-2007 04:33 AM - edited 03-14-2019 10:26 PM
I have a Sip connection between a Cisco 2811 and a AudioCodes (Carrius) system. Call can be completed in both directions without any issues. Our issue is faxing. A fax will complete fine if the recieving fax is not set for "auto receive". From what I can tell the RTP stream is established and then the T38 negotiation occurs. When the fax is set for auto this does not occur. Has anyone experienced this issue?....Is there a way to "delay" the T38 setup to allow for the g711ulaw call to be established first...? Any help would be appreciated..
Thanks,
Joe
07-12-2007 11:27 AM
Make sure your gateway has this configuration:
voice call send-alert
voice rtp send-recv
!
voice service voip
allow-connections h323 to h323
h323
emptycapability
no telephony-service ccm-compatible
ip circuit max-calls 100
ip circuit default only
no ras brq
h225 timeout tcp call-idle value 0
h225 h245-address on-connect
h225 connect-passthru
call start slow
session transport tcp calls-per-connection 1
h245 tunnel disable
h245 caps mode restricted
modem passthrough nse codec g711ulaw
After this, you need to delete your H.323 gateway configuration from Cisco CallManager and configure this as a Non-Gatekeeper controlled InterCluster Trunk.
When this is done, the Cisco CallManager seems to respond with the H.245 TCS right away and the call is established.
Note: In 4.1.3, you have the option to configure Cisco CallManager to send the TCS right away and not wait to receive it but there is no check box for this in Cisco CallManager 3.3.3. This is why it works with the Trunk, whose default behavior is to send the TCS right away.
Refer to T.38 Fax Relay for Voice over IP H.323 for more information.
07-12-2007 12:08 PM
Thanks for the reply...we are not using h.323 we are using SIP and there is no CallManager involved...this is simply a cisco SIP gw to a Carrius SIP gw.
Thanks,
Joe
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