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the extension under eSpace U1911 make an outgoing call to PSTN, but the called phone show a fragmentary calling number

Publication Date:  2014-11-17 Views:  97 Downloads:  0
Issue Description
Our U1911 is connected with PSTN through PRA trunk.
The topology like this:

The extension under our eSpace 1911 make an outgoing call to the phone under PSTN, ringing and connection is normal, but the calling number showed in called phone is not right.  The incoming call is correct.

For example, extension 1 make an outgoing call to mobile phone B. B show a calling number with 249726, the right number should be 24972600.
Alarm Information
the calling number showed in called phone is not right.
Handling Process
  1. we suggest our partner to trace the signling from LMT. To check the calling number sent by U1911 is right or not.
  2. Then we fed this result to our partner and gave a suggestion that checking it from PSTN. At last, engineer from PSTN checked this issue, and told us that their system use a special rule to show calling number, and their hoped calling number is 600, but not 24972600. And PSTN don't like to change their rule and hope we could adapt their current rule.
Root Cause
the connected PSTN have a special rule, and cause we need to adapt their rule.
  1. they use prefix 8 for outgoing call to PSTN. I add a number changing rule(to delete the former 2 digits), then attach this rule to prefix 8 function.
  2. short number 67600, matching long number 24972600. I disable the display long numbe function. so the calling number will change to 600 when make an outgoing call.
  3. and this issue was sloved finally 
First to check the format that out device used.
Second, check it matching with PSTN or not.
At last, try to match them with each other.