Random second call on the line when agents are on the phone

At random, we are seeing agents get a second call while they are on the phone with a customer. Not sure how or why. The way the vendor who deployed it set everything up, they said it should only send one call to one endpoint at the time. They won’t help us troubleshoot or fix it, so hoping you guys might be able to point me in the right direction.

The agents are on a call, look down and see that there is another call coming in. They ignore it and it rolls over to another agent after 12 seconds of not being answered.

Does anyone know what areas I need to look at in order to pinpoint / resolve the issue?

Asterisk 11.7.0
Loway QueueMetrics - 14.03.3 - B: 4836 2014-04-03 13:24
O.S.: Linux - Ver: 2.6.32-220.13.1.el6.x86_64 - amd64
Endpoint: Yealink T46G

Full log shows:

Agent 1: Call IDs C-00074c7f and C-00074c82
[2014-11-01 16:04:02] VERBOSE[18895][C-00074c1c] file.c: – <SIP/1019-000ccf2d> Playing ‘custom/XPB_Zip_2579.sl
in’ (language ‘en’)
[2014-11-01 16:10:13] VERBOSE[8208][C-00074c7f] app_queue.c: – Called SIP/1019
[2014-11-01 16:10:13] VERBOSE[8518][C-00074c82] app_queue.c: – Called SIP/1019
[2014-11-01 16:10:13] VERBOSE[8208][C-00074c7f] app_queue.c: – SIP/1019-000ccfe5 is ringing
[2014-11-01 16:10:13] VERBOSE[8518][C-00074c82] app_queue.c: – SIP/1019-000ccfe6 is ringing
[2014-11-01 16:10:14] VERBOSE[8208][C-00074c7f] app_queue.c: – SIP/1019-000ccfe5 answered SIP/XBET1-SIP-OUT-000ccfe1

Agent 2: Call IDs: C-00074ae8 and C-00074af5
[2014-11-01 15:57:13] VERBOSE[25617][C-00074ad3] file.c: – <SIP/1013-000cccb4> Playing ‘custom/XPB_Zip_2579.sl
in’ (language ‘en’)
[2014-11-01 15:57:45] VERBOSE[27461][C-00074ae8] app_queue.c: – Called SIP/1013
[2014-11-01 15:57:45] VERBOSE[28001][C-00074af5] app_queue.c: – Called SIP/1013
[2014-11-01 15:57:45] VERBOSE[27461][C-00074ae8] app_queue.c: – SIP/1013-000ccceb is ringing
[2014-11-01 15:57:45] VERBOSE[28001][C-00074af5] app_queue.c: – SIP/1013-000cccec is ringing
[2014-11-01 15:57:46] VERBOSE[27461][C-00074ae8] app_queue.c: – SIP/1013-000ccceb answered SIP/XBET2-SIP-OUT-0

My guess is since you are using QueueMetrics and they handle all the login that things are not set correct to ignore second calls.