Hi netpros,
I have done some troubleshooting over the weekend so I'm passing this information on to you to hopefully speed up resolution.
The issue is with incoming faxes into our office. All fax machines are hanging off 2 analogue voice gateways (Cisco VG248). There are also two voice routers connecting to two independent Telstra ISDN services servicing the same extension range (02 77777XXX and 02 88888XXX, where XXX is the user/fax's extension number). The first one is the one we use for our inbound calls.
All faxes coming in via 77777XXX are not getting through, though if we send the faxes to the same machines on 88888XXX they seem to work.
I had a look at the router and found that there are errors happening on the ISDN line as evidenced by the show controller E1 command. This is the case on both voice routers. The example show is from the 77777XXX router.
E1 1/1 is up.
Applique type is Channelized E1 - balanced
No alarms detected.
alarm-trigger is not set
Version info Firmware: 20050620, FPGA: 16, spm_count = 0
Framing is CRC4, Line Code is HDB3, Clock Source is Line.
CRC Threshold is 320. Reported from firmware is 320.
Data in current interval (650 seconds elapsed):
0 Line Code Violations, 0 Path Code Violations
339 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins
339 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs
Total Data (last 24 hours)
0 Line Code Violations, 0 Path Code Violations,
45239 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins,
45239 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs
Thereis technical documents on the Cisco site detailing that Slip Errors are able to disrupt fax communications but not voice calls. This is exactly what we're experiencing at the moment. Following is the link to the technical article. Please can you refer to Section 3 (SLIP errors): http://www.cisco.com/en/US/tech/tk652/tk777/technologies_tech_note09186a0080114565.shtml#topic3-3
I've been able to put in a workaround by disabling the fax relay mode on all Analogue Gateways' ports that connect to fax machines but this hasn't resolved the issue as some of the machines still can't receive faxes even with this setting disabled.
Your help is much appreciated !!
