Unavailable numbers on voip phone -3CX

sadiya yousaf
sadiya yousaf used Ask the Experts™

We are using voip phone and provider is 3CX . Currently we are receiving a lot of phones call with unavailable number. 3rd party support is saying that everything is ok from their side. When we ask customer if they are ringing from withheld number , most of them say that they are not ringing from withheld number. Please advice what could be wrong
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Software Engineer
Distinguished Expert 2018
Step 1:  you can tap the wire (f.e. using wireshark , or other packet capture tool) and record a session to tell IF there is a number mentioned in CALL packet.

If there is no number there or a 0.. then there is no number. presented to the phone. If there is a number there then the phone is not presenting it.


I have asked third party for packet filtering , it was right move as soon as I spoke the term , the guy said that it was going to be our next move even though in the previous call he had kind of closed the call

1) Current versions of 3CX< you can do the Wireshark capture from the 3CX "Activity Log" screen.
- Click "capture"
- make your test call
- STOP the capture
- a few seconds later you'll get a URL to download the .pcap file. Use Wireshark on any machine to open this to examine.

2) If you are definitely receiving the sender-CLI but it isn't displaying, you will need to check your "Sip Trunk - Inbound Parameters" tab. There are lots of options here and you can easily break what was working so FIRST take careful notes of the settings as they are now. It's probably going to be best if you check with your SIP trunk supplier to see which fields they're sending. You need to match the "CallerNum" parameter to a suitable source field, usually "From:User Part" but it could be "Remote Party ID - Calling Party: User part", for exampe, or P-Asserted-Identity.   NOTE that these should be correct, however, if the sip trunk supplier is 3CX "approved" and you used the correct template to set up the trunk.
nociSoftware Engineer
Distinguished Expert 2018

i found a great tool to track COIP traffic. lookup sngrep if it is in your distro. This is a very accessible tool to collect data on SIP.

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