I trying to get Fax over IP using T.38 properly running.
I have a CCM 4.1.3 with a Fax server connected via a trunk. The fax to external PSTN are working when I send them to the H323 gateway. The problem now it only works if the gateway is a 3725 or a 3745. When I try to use a 2811 or a 3825 it doesn't work. The fax connection gets established but after exactly 20 seconds (and it is always 20 seconds, so looks like a timeout timer) the connection gets dropped and fax never arrives.
On the all the router the configuration is similar:
voice service pots
fax rate disable
voice service voip
fax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback none
modem passthrough nse codec g711ulaw
Actually the configuration shouldn't be so complecated as the fax is only outgoing to the PSTN. Also I tried different IOS version ranging from 12.3 to 12.4.
So now I am out of ideas, so your input is desperately waited for.
Thanks for the help in advance.