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Only main number displays while making outgoing call to PSTN via PRI

Publication Date:  2012-08-02 Views:  146 Downloads:  0

Issue Description

In a brief overview of the UC project, the equipment Softco5500 with version V100R002C05SPC100, interconnected with a local PSTN via PRI signaling. The configuration on the Softco5500 was correctly configured to display a long number while making outgoing calls, but the output or the final displaying number was always a main number and this resulted in number plan mismatch whereas the call was set up correctly.

Alarm Information

The trace tool “UCMaint” was used to get outgoing PRI signaling traces while launching an outgoing call. We find out that the calling number included a “setup” message which was displaying the long number as expected, and similar traces were done in the PSTN side, resulting in an error message “calling party format error”.

Handling Process

Execute the following two commands to change the value of above two fields of parameter:
1) config softargu type 257 value 1 //change the value of field”Numbering plan identification” to be “1”;
2) config protocol pra officeno 11 typeofclinumber unknown  //change the value of field ” Type of number” to be “0”;
After running the above commands, the fields of parameter contained in “setup” message from Softco are changed successfully as required according to trace. Please refer to attachments.

Root Cause

According to the PRI signaling trace from the Softco side, the calling number was a long number as expected, which means the configuration of the displaying policy was correct in Softco side, so the number must have been changed in PSTN side and two possibilities to confirm this are as follows:
1) Maybe it is configured purposely to change the calling number to main number in the PSTN side;
2) Part of the parameters contained in the “setup” message from the Softco doesn’t match the requirements of the PSTN side and the calling number was then changed to display the main number because of the mismatch;
After confirming with PSTN side, the first possibility was excluded. The error “calling party format error” from PSTN side was analyzed, finding that two fields of the parameter included in the “setup” message from Softco were incorrect:
1) The field “Numbering plan identification” is required to be “1”, which actually means “ISDN numbering Plan E.164/E.163”, but the received value was “0”, which means “unknown”.
2) The field “Type of number” is required to be “0”, which means “unknown”, but the received value is “4”, which means “subscriber number”;


Softco interconnection with the PSTN via PRI is an interactive work for both sides (PSTN and IPPBX provider), so engineers of both sides should be present to confirm the requirements and details for integration. The newly added equipment like Softco should normally be put in “user” side and should match the requirements of the “network” side equipment of the PSTN;