FAX is usng relay instead of t.38

[rejackson]

I have a fax on one G700 in a stack and a PRI on another g700 in the stack. The faxing in the IP-codec for inside the network region is set for t.38 but outbound faxes are using fax relay. The trace shows it first in the intra region link between the MVOIPs in the two G700s. Then shows it again as the call goes out, and fails.

If I reroute the call through another network region it goes out t.38 and works.

Is there something I am missing about configuration codecs for calls between members of a media gateway stack?

 

[kyle555]

Good question. Maybe I'm wrong here... but I ***THINK*** (and may totally be wrong) a G700 stack is pure TDM from a fax to the PRI in that stack.

Considering that T38 is a specification for fax over IP, you may never have actually gone IP between that 1 700 with the analog card and the other with the PRI - if they are in fact stacked in the back with stacking cables.

Maybe the T38 is a red herring for the fax failing. Do any other analog devices go out that particular PRI OK? Stuff like "list measurements ds1 log 1V2" for PRI card in slot 2 of gateway 1 would show slips, and making sure your clock source is set to that PRI on that gateway is something far more important (in my opinion) to check for analog transmission than the whole t38 thing if the network is solid.

 

[rejackson]

Thanks Kyle,
I have looked at the PRI and do not see any problems there. The trace surprised me with the voip.


The list trace I have is in screen shots, not text, otherwise I would paste it in here. Here is a summary

dial nnnnn route ars
term trunk group 36
G711MU IGC created
rgn 36 (addres of mvoip) GW27
rgn 36 (address of mvoip) GW26
xoip options fax:relay modemff tty:US (igc)
xoip (address of one mvoip)
xoip options fax:relay......(igc)
xoip (addres of the MVOIP)
dial nnn
route-pattern ....
calling
proceed trunk...
alert trunk
active trunk
start fax relay aux"none tone:CED (igc)
from voip (address of one voip)
start fax relay .......(igc)
from voip (address of the other voip
voip data from (address of voip on mg with the fax)
jitter 0 0 0 0 0...
pkloss 0 0 0 0 0 0...

until the call drops

It does show * in the packet loss a lot. I am also wondering about the IGC created and referenced. Is it like Inter Gateway connection maybe?

 

[kyle555]

Then you are most certainly going over IP, and * in packet loss means you're losing all of them. Is the IP of the voip address that of the G700's voip interface?

In each gateway form you have the network region assigned, as you would in the IP network map. Are you sure that in both media gateway forms that they have the same network region such that they ought to follow the "intra-region" settings?