"No Fax Detected" Fax over IP Trunks

[wobbly_head_bob]

I'm experiencing intermittent problems on my 3300 network.  Occassionally a fax machine will send and receive faxes fine, then all of a sudden it will just stop receiving faxes and instead get a "NO FAX DETECTED" message on the machine.

I've ensure my "Fax Configuration" form is using:

Profile #2:  Fax Rate:  14400 V.17 14400bps:  High Speed Redun 1:  Low Speed Redun 3:  ECM Disabled:  NSF Disabled:  NSF Vendor Code BLANK:  NSF Country Code BLANK:  Label  T.38

This "NO FAX DETECTED" error, while intermittent is prevalent in my network, as I have 35+ 3300s....with who knows how many fax machines off of each.  Anyone have anything on this issue?

[ianbt001]

This is usually a clocking issue, check where your clocking from ( source) and check logs to see if its slipping etc.  try command "dtstat read  x  x   x  x " to check.  x being plid number of link.

[wobbly_head_bob]

I'm not so sure..

While I do have DS1 formatters at each of my sites, the voice calls are being transmitted just fine.  For S'n'Gs I ran the DTSTATs for the last 24 and it came back absolutely clean on either end.  I'm not quite sure what exactly I can check on the IP trunking side, but I'm positive that I'm having some sort of issue with transmitting/receiving the T.38 protocol. In a particular call three switches could be used:

(**PSTN fax call**)--> [TrunkingGateway3300] -->(ip networking) --> [VoiceGateway3300] -->(DS1 formatter) -->[Destination3300] (BeepBopBooop...no fax detected!!!)

I had the technician on site turn silence detection off, error correction off and V.17(medium speed) on in the actual fax machine.  This appeared to work at least for now, who knows, the problem like I said has been intermittent and seems to come and go all across my network.

[ralph]

How are the faxes coming into your system? 
PRI?  CO?
Do you have the same problem just faxing internally across the network?

Ralph

[wobbly_head_bob]

The faxes come in from the outside world via PRI.

Internally, DID:DID, yes I do experience the same problem when the fax call needs to traverse the IP trunks.  If I have two faxes within a switch, there isn't an issue.  If I have two faxes separated by DS1 only, no issue.  If I have to hop via IP I will more often than not see "no fax detected"

[ralph]

Are you getting T.38 errors in the logs?

Ralph

[wobbly_head_bob]

If you can direct me to which logs would show these, I'd appreciate it.  Maintenance/Software logs don't show anything at all really pertaining to T.38, or anything I can pinpoint to being a fax. 

[Mattmayn]

Stupid question, you do have T.38 licensing and DSP II cards installed on each 3300 involved don't you?