Outbound calls fail depending on carrier

[jimmernet]

Hi We're using Twilio Elastic SIP Trunks to route out calls to the USA. Calls to eg verizon cell phones work fine. Calls to T-mobile always result in "Busy". I've searched the web and found this lone article reflecting this issue with Asterisk systems. https://community.asterisk.org/t/outbound-calls-fail-depending-on-carrier/86870 Has anyone else seenthis issue - any further clues as to a workaround..? Thanks!

 

[leejor]

Have you checked the 3CX Activity Log to see if your provider responds differently on a call to a T-Mobile number? If you get the same reply, but hear busy, then I would contact your provider to see if they have a suggestion, or can help troubleshoot. You may not be the only one of their customers having this issue. It could be something that T-Mobile does not like, on the call (caller ID?), or, it could be an issue with the chosen route, that your provider uses, to reach T-Mobile numbers.

 

[YiannisH_3CX]

Hi @jimmernet

As @leejor suggested this is something you need to discuss with your provider as it seems that their routing to T-Mobile is not working properly. Providers are not always directly connected to other providers so it might be the upstream provider that Twilio is using that has the issue. This is also something that Twilio needs to clarify.
Since your trunk is set up correctly and all other calls work I do not see this as a 3CX issue.