Super G3/G4 Fax

[Gordon Ross]

Is it possible to get Super G3 or Super G4 faxing to work over CUCM/VoIP ?

GTG

[Ayodeji Okanlawon]

Gordon,

Cisco IOS gateways with Cisco IOS Release 12.4.4T and later offer support for Super Group 3 (SG3) fax transmissions when T.38 or Cisco fax relay are configured; however, only Group 3 speeds are negotiated.

If it is necessary to transport SG3 high-speed faxes at their native speeds, then modem passthrough must be used. With the release of Cisco IOS version 15.1.1T, a new feature will provide native support for SG3 faxes by T.38 fax relay.

See detailed asnwer here.. I dont think Super G4 is supported though. Cant see any reference to it.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/8x/gateways.html#wp1064689

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"There is a wideness in God's mercy Like the wideness of the sea.There's a kindness in His justice Which is more than liberty"

[Aaron Harrison]

Hi

If you are talking ATAs - then definately not. Expect v.slow fax... like 9600k.

IOS based gateways have lots of features (in t.38 mode) aimed at preventing faxes from negotiating complex connections, forcing them to negotiate G3 rather than Super G3, disabling ECM etc. so although you will get better performance from a properly configured IOS gateway over an ATA, I would always set expections quite low.

If speed is really important it's probably best to look at a proper server fax solution rather than hoping to push the performance of a fax machine over IP.

It'll save some trees as well :-)

Aaron

Aaron

[Gordon Ross]

One of the problems I'm getting, is that many standard fax machines try and use Super G3/G4 and won't reliably down-speed to 14.4 Kb/s. This isn't with just cheap fax machines, but also higher cost/spec fax machines too.

GTG

[Gordon Ross]

On my CUCM setup, I can't get close to 33.3 Kb/s speed with modem pass-through.

We're trying to play with T.38 at the moment, but, that's giving speeds worse than modem/fax pass-thru !

GTG

[Ayodeji Okanlawon]

What IOS are you on?  are you using VG 224, 204, 202? ?Please note that modem passthrough and modem-passthrough are not the same. Try modem passthrough wihtout the  hyphen

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"There is a wideness in God's mercy Like the wideness of the sea.There's a kindness in His justice Which is more than liberty"

[Gordon Ross]

I'm trying with the latest IOS (15.2-3.T1)

What's the difference between the two modem passthrough commands ?

GTG

[Ayodeji Okanlawon]

one is configured with modem pass-through, the other is configured with modem passthrough(this is the one you shuld try)

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"There is a wideness in God's mercy Like the wideness of the sea.There's a kindness in His justice Which is more than liberty"