[cisco-voip] CME fxo-gs inbound call rings again if far-end hangs up first

[John P Callahan]

We have a remote site with a 2811 running CME attached to several POTS 
lines using ground-start signaling on FXO ports.  Each voice port does a 
plar to an IP phone extension.

Everything works great except on one of the lines on inbound calls, if 
the far-end hangs up first, CME sees another phone call about 2 seconds 
with the same caller-id but if the IP phone user picks up they just hear 
a dial tone.  No problem if the IP phone user hangs up the call first or 
if the call is originated from the IP phone (outbound call).  The most 
common scenario is someone calls, the user isn't there, the call gets 
handled by Unity Express, the caller leaves a message, hangs up - then 
1-2 seconds later the phone rings again, no answer, goes to UE, records 
a few seconds of dial tone.  IP phone shows "2 New Missed Calls" for 
what was really just one call.

I have confirmed that the problem follows the line and not the port in 
the 2811 that it is connected to.  Tried ports on each of the HWICs - 
same problem with that line.  All the lines come in on a 25 pair cable 
and terminate in a 25 RJ-11 block grounded to the same ground as the 
rack the 2811 is in.

I filled a TAC case and we cranked up the debugging, did a "timing 
sup-disconnect 50" and "timing guard-out 2000" on the port, all to no 
effect.

I filed a repair request with the telco and they reported no problems 
with the line.

The case has been stalled since the occupant of the office moved out and 
they just wanted the number to go to an announcement - now someone is 
back in the office using the same phone number and having the same problem.

My background is more in the network world than the telco world so I am 
wondering if any of you wise folk have experienced a similar problem and 
can suggest what I ask the telco to check before I send them out again?

Thanks in advance,

John