3cx cloud Version 20.0 Update 7 (Build 1080 Release) issue with incoming calls voip.ms

[ronenba]

I am hosting my 3CX on Amazon, located in the Montreal server

Seems when I try to add a sip trunk from voip.ms with DNS pointing outside of canada i can make outgoing calls but cannot receive them

If I change the DNS to a Canadian DNS seems to be working fine

any ideas how to address the issue with sip trunk outside canada dns ?

this is the error when i was using sanjose dns or the same if i was using from Washington dns server:

Unidentified Incoming Call. Review INVITE and adjust source identification:. INVITE sip:[email protected] SIP/2.0. Via: SIP/2.0/UDP 208.100.60.41:5060;branch=z9hG4bK1a3bcf1b;rport=5060. Max-Forwards: 70. Contact: <sip:[email protected]:5060>. To: <sip:[email protected]>. From: "TORONTO ON" <sip:[email protected]>;tag=as78d764a7. Call-ID: [email protected]:5060. CSeq: 102 INVITE. Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH, MESSAGE. Content-Type: application/sdp. Date: Fri, 23 Jan 2026 17:12:23 GMT. Supported: replaces, timer. User-Agent: voip.ms. Remote-Party-ID: "TORONTO ON" <sip:[email protected]>;party=calling;privacy=off;screen=no. X-Dest-User: 350401_sos. Content-Length: 270. v=0. o=root 932425989 932425989 IN IP4 208.100.60.41. s=voip.ms. c=IN IP4 208.100.60.41. t=0 0. m=audio 12338 RTP/AVP 0 18 101. a=rtpmap:0 PCMU/8000. a=rtpmap:18 G729/8000. a=fmtp:18 annexb=no. a=rtpmap:101 telephone-event/8000. a=fmtp:101 0-16. a=ptime:20. a=sendrecv

 

[KyriacosS_3CX]

Hello,

Please check if an OK call and a fail call SIP requests differ.

Also enquire about this with the SIP Trunk provider - perhaps they provide different end point IPs depending on what region you are, and when changing DNS servers you are talking to some server you are not authorized to do so, or that uses different configs.

 

[YiannisH_3CX]

Are you using a IP based trunk or registration based? If you are using an IP based trunk please switch to registration.
If you are already using a registration based trunk then please contact Voip,MS and ask them why they do not add rInstance in this specific scenario!

Also make sure that the DIDs in your PBX are added in the 10 digit format.

 

[ronenba]

using registration based, seems if i setup the sip from voip.ms with DNS outside canada it is not working for incoming calls only. I spoke to them, and they saida firewall, or something, is blocking on my end, i change it to Toronto or any location within canada and it started working (btw I use the same settings, outbound rules, I tried USA DNS did not work)

Anything I may need to do on the PBX?

 

[YiannisH_3CX]

If you are getting the error you posted above when you attempt an inbound call then you are having call source identification issues and not issues with firewall. It seems that Invites coming from VoIP.MS when using a PoP outside of Canada are formatted differently. Make a pcap with an inbound call coming from a Canadian PoP and then to the same when you are using a USA one. Compare them to see if there are any differences.