Original caller ID lost when queue forwards unanswered calls to Vapi via VoIP.ms or Twillio trunks

[farman khan]

Hello 3CX Support Team,

We use 3CX V20 with Twilio and VoIP.ms trunks. When an unanswered queue call forwards to our Vapi AI assistant, Vapi displays the main Twilio trunk number instead of the original customer’s number.

Example call:

• Original caller: +1....81660
• Dialed Twilio DID: +1....784316
• Main Twilio trunk number: +1....032835
• Queue: 80029 — TEST QUE
• Queue timeout: 15 seconds
• No-answer destination: +1....014788, our Vapi assistant

The incoming call reaches the queue through 3CTEL Twilio. The forwarded leg uses the outbound rule “Outbound Calls voip.ms” and leaves through VoIP.MS.

The 3CX report shows caller 1660 and forwarded destination 4788 correctly. However, Vapi shows 2835 under Customer Phone Number.

Settings reviewed:

• Outbound-rule caller ID: blank.
• VoIP.ms default outbound caller ID: blank.
• Include diversion header support: enabled.
• Exported VoIP.ms template: FromUserPart = $AuthID and RemotePartyIDCallingPartyUserPart = $OutboundCallerId.

Could you confirm the correct supported configuration to preserve the original caller ID for this queue-forwarding scenario? Specifically, should the RPID number mapping use $OriginatorCallerId, and how should we apply that change to the existing trunk?

Please also advise which SIP headers or diagnostic traces we should inspect to determine where the caller number changes. We need this to work dynamically for every customer.

Thank you.

 

[Alphabetic]

Thread 'Voip.ms CallerID'

Jul 22, 2025

Hi,
We have trunks with Voip.ms.
I am having some issues getting the inbound callerid to get forwarded to CellPhones.

if someone calls in and the call gets sent to the extension. That extension could have a mobile number, but the forwarded call doesn't get the original caller id. it just gets the standard outbound. "company name & phone number"

I have setup a test inbound number to goto an extension that will go out on a specific trunk that I can play around with.
there were more options in v18, but now that I am on v20, the Caller ID options are just

From: Display Name
Remote...

• JArchibald
• callerid outbound caller id
• Replies: 3
• Forum: US

suggests they dont support CLIP No Screening which is what you need, its an old post so you'd have to ask them first if this is still the case.