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Calls from PSTN fails using MGCP gateway

Tan Jay Sern


I have configured my MGCP gateway to register with my CUCM. However, only calls from CUCM is successful whereas calls from simulated PSTN fails.

Please find attached debugs and gateway configs.

Appreciate your comments. Thanks.

26 Replies 26

Hi, the called number received from simulated PSTN is "Called Party Number i = 0xC1, '5553003' " but your extension is 2003 not 3003. that is causing the issue.


If you configure 3003 instead of 2003, it would ring the phone. Please check.

//Suresh Please rate all the useful posts.

I've tried, its not ringing.

I only got it working if I change the external phone mask to 2XXX and the DN to 2XXX, but I wanted to use DN 3XXX as it will differentiate my HQ phone from my BR phone

It is confusing. can you brief more on this please?

//Suresh Please rate all the useful posts.

Basically my HQ uses DN 2XXX, with external mask +555115552XXX, BR uses DN 3XXX with external mask +665215553XXX, if I call 5553XXX, it will fail, however, if I change it to 2XXX for both DN and external mask it works. I am also getting confused.

External mask is nothing to do with inbound calls.

can you check if there is any translation pattern (beginning with 555) to convert the number from 5552XXX to 2XXX?


What I guess is, instead of passing only 4 significant digits, all digits are received & processed in CUCM.

//Suresh Please rate all the useful posts.

I thought translation pattern is call from CUCM phones to PSTN. Correct me if I am wrong, my knowledge in voice not that good, I could not see any translation pattern beginning with 555. As for Called party transformation pattern, I could see some pattern,

\+55511.XXXXXXX with predot discard digits.

and calling party transformation pattern with



also with predot discard digits

it is now better to collect CCM traces for a test call for BR site. also collect the debug isdn q931 log from the MGCP gateway at the same time.Please include the calling & called number.

//Suresh Please rate all the useful posts.

Without going deeper in problem (we already have so much confusing info smiley) - why don't you just replicate HQ translations which you mentioned for your BR location with appropriate modifications?




Hey guys, issues solved. Just a silly cable issue, I changed the cable and everything works miraculously.

Dragan Ilic

This isdn debug - it it for outgoing call?

And ccapi - for incoming?

Can you give a little bit more details...




Both the ISDN and ccapi is for outgoing. 

Please find ISDN debug for MGCP GW

*Apr  8 17:30:58.131: ISDN Se0/0/0:23 Q931: RX <- SETUP pd = 8  callref = 0x0095 
        Bearer Capability i = 0x8090A2 
                Standard = CCITT 
                Transfer Capability = Speech  
                Transfer Mode = Circuit 
                Transfer Rate = 64 kbit/s 
        Channel ID i = 0xA98381 
                Exclusive, Channel 1 
        Progress Ind i = 0x8583 - Origination address is non-ISDN  
        Calling Party Number i = 0x4180, '5554444' 
                Plan:ISDN, Type:Subscriber(local) 
        Called Party Number i = 0xC1, '5553003' 
                Plan:ISDN, Type:Subscriber(local)
*Apr  8 17:30:58.143: ISDN Se0/0/0:23 Q931: TX -> RELEASE_COMP pd = 8  callref = 0x8095 
        Cause i = 0x8081 - Unallocated/unassigned number


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