Calls drops when transferring to mobile phone

totaycs

Bronze Partner
Joined
Oct 2, 2025
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Hi all,

We’re running 3CX v20 with an AAPT SIP trunk. Direct outbound calls to mobiles and landlines work fine.

From SIP logs:
Direct mobile dial = works.
Transfer to mobile = fails. 3CX sends a BYE (UserTerminated) shortly after.

What I’ve done so far:
Checked outbound rules → mobiles route correctly.
Verified in the exported trunk XML that IsSupportReinvite=0 and IsSupportReplaces=0.

Anyone have similar issue?
 
Blind transfer or attended?

How many SC you got?
 
Could the issue be the caller ID , being sent, when doing a transfer? Check the 3CX Activity log to see if your provider is rejecting the call , for that reason. Different transfer types send different caller ID, you may be trying to send the CID of the extension.