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t.38 fax problems with Nashuatec FP 103 over SIP provider trunk

c.hennrich
Level 1
Level 1

Hi all,

I have currently massive problems with several fax devices, but mainly Nashuatec FP 103 using a SIP Provider Trunk with T.38. The Fax is sent several times and also sometime received up to 10 times. Some pages are half empty and so on. I guess a problem with ECM. Does anybody know the Nashuatec FP 103 and how to disable ECM? I can’t find something in the manual. I guess I need to set some DIP switches.

My setup:

VG224(IOS 15.1.3T) <-CA controlled MGCP-> CUCM 7.1.3 <-SIP Trunk-> SIP Provider/COLT

This setup enables me to use protocol-based T38. Also an IOS Based MTP is used, which is configured with passthrough, so that T.38 faxes can work. There was a Bug CSCtj03639, using MTP. I received a fixed IOS version, so that issues should be resolved. The MTP is running on a VG 3925 co located in the site, where the VG224 resided. I was able during testing to send 30 pages over 60 minutes without error. I use G711 outbound and inbound for faxing. No early offer. No CUBE between, direct CUCM SIP trunk connection.

Sip call flows are looking well. I guess that the problem is in the higher levels of the Fax communication itself. We need to use MGCP, because the operations team should be able to use the CUCM interface to setup call restrictions. Therefore these VG224s are not pure SIP. But it should also work with CA controlled MGCP gateways. The MGCP debugs are also looking good.

Modem pass-through is disabled at the VG224 to not interfere with T.38 as it is NSE based and the SIP provider does not understand or use any NSE based communication.

Any help, idea or suggestion is very much appreciated. Thank you all in advance!

MGCP Configuration:

ccm-manager fallback-mgcp

ccm-manager redundant-host 10.140.25.17 10.140.24.17

ccm-manager mgcp

no ccm-manager fax protocol cisco

ccm-manager music-on-hold

ccm-manager config server 10.140.25.11

ccm-manager config

ccm-manager download-tones

!

mgcp

mgcp call-agent 10.140.25.18 2427 service-type mgcp version 0.1

mgcp dtmf-relay voip codec all mode out-of-band

mgcp rtp unreachable timeout 1000 action notify

mgcp ip qos dscp cs3 signaling

mgcp package-capability rtp-package

mgcp package-capability sst-package

mgcp default-package fxr-package

no mgcp package-capability res-package

no mgcp timer receive-rtcp

mgcp sdp simple

mgcp fax t38 ls_redundancy 2

mgcp fax t38 hs_redundancy 1

mgcp fax-relay ans-disable

mgcp rtp payload-type g726r16 static

mgcp rtp payload-type nte 101

!

mgcp profile default

sh mgcp:

MGCP voip modem passthrough disabled

MGCP voaal2 modem passthrough disabled

MGCP voip modem relay: Disabled

MGCP T.38 Named Signalling Event (NSE) response timer: 200

.....

MGCP T.38 Max Fax Rate is DEFAULT

MGCP T.38 Fax is ENABLED

MGCP T.38 Fax ECM is DISABLED

MGCP T.38 Fax NSF Override is DISABLED

MGCP T.38 Fax Low Speed Redundancy: 2

MGCP T.38 Fax High Speed Redundancy: 1

MGCP Fax relay SG3-to-G3: ENABLED

MGCP Fax relay ANSam suppression: ENABLED

2 Replies 2

c.hennrich
Level 1
Level 1

Thanks to a colleague and this document, the MTP is now not invoked anymore:

mgcp dtmf-relay voip codec all mode nte-ca

mgcp package-capability fm-package

http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a00808b6ca6.shtml

But we still have issues with Faxing. Do you have any other ideas?

BR

Could be a problem with the IOS on the VG224.

Check the version you are running with the bugtoolkit and check for bugs with T38

I have had several problems in the past with T38 and IOS bugs