Showing results for 
Search instead for 
Did you mean: 

Certain Incoming Long Distance Calls dropping

Level 1
Level 1

I have installed a UC560 about 2 months ago for one of our customers who is a Travel and Tourism office.  The customer went from Analog lines on the old phone system, to a PRI with the UC560.   They are using the SPA508 phones, and the UC560 has ver 15.x.   They customer has started getting complaints via email from prospective tourists that they cannot get through to their office by phone.   It occurs on all DID numbers, not just their main published number.   Outbound local and LD calls are not affected, in fact, the customer can call the prospective tourist back using the UC560 and phones.

The callers state that they hear 2 rings, followed by a dial tone, and disconnect.  The q931 debug on the UC560 shows a call connecting, lasting about 10-12, followed by a Normal Call Clearing code.  Our translations department sees a disconnect coming from the calling party when they look at the D-channel information. 

Has anyone experienced a problem such as this?

5 Replies 5

Level 1
Level 1

Can you do a sho controllers e1 and post the output.

Is it a full PRI or fractional?

I have seen something similar but it affected all calls. The issue was a mismatch on CRC4 config. I have CRC4 off and the carrier had it on.

I will post the config later. But the the PRI is setup as T1, 23 Bchannels, and primary-ni. The Central Office switch is set for NI2. I have seen a mismatch causing all calls to have problems, but not just a minority of the Long Distance calls that the customer receives.

No local calls or LD calls made from within our Telco footprint (in or out of state) have a problem calling in.

Robby Harrell

CenturyLink (formerly Embarq)

Business Service Tech III

LAN, WAN, VoIP, Firewall, Video Conf.

Cell 252-813-1719

104 East King St.

Edenton, NC 27932

If you are running the latest software pack, it could be caused by the new toll-fraud app...

Try disabling toll-fraud app completely:

Conf t

voice service voip

no ip address trusted authenticate

Note:  (other setups for toll-fraud)

Explicitly enable those source IP addresses from which you would like to add to the trusted list for legitimate VoIP calls.  Up to 100 entries can be defined.  This below configuration will accept calls from those host, as well as from the network  Call setups from all other hosts will be rejected.  This is the recommended method from a voice security perspective.

conf t

voice service voip

ip address trusted list



Configure the router to accept incoming call setups from all source IP addresses.

conf t

voice service voip

ip address trusted list


Actually,  the IOS version is uc500-advipservicesk9-mz.150-1.XA2.  I do not see that command there.  The calls came through with our PRI test equipment connected to the PRI, so I will open a TAC case in the morning.


Your on an older SWP with the IOS that didnt introduce the toll fraud voice service viop command you were asked to check.

So that makes sense at least.