Hi All,
I'm a bit puzzled by this one. I'm 99% sure it's the firewall but exactly what is doing it I don't know.
As above, outbound calls only work after an inbound call has been made and this is only for a short window of time. The error in the event log for a failed call is:
"...has failed. 0.0.0.0 replied: 408 Request Timeout; internal"
I've done a Wireshark trace and examining the results for port 5060 shows that the INVITE is sent from the PBX to the SIP provider IP but nothing seems to come back/no ringing message ever gets sent. Speaking to the SIP trunk provider, they can't see anything on their end either so it would seem that everything stops at the router/firewall.
Additional setup info:
3CX Version: 18.0 update 2
Server OS: Windows 10 Pro
System is hosted on premises
Trunk provider: Gamma
The router/firewall is a Cisco Meraki MX85, The firewall check comes up as all passes except for SIP ALG which I'm told is normal for this router and it doesn't have the SIP ALG function. Unfortunately, I do not have control over this router and it's managed by a provider in a different timezone making life tricky meaning that implementing any changes can only be done in a short timeframe due to any changes also needing approval. I just need to know what to request or ask of them although I did ask them today if they could see what was happening to the invite messages coming from the PBX.
I remember seeing something about UDP flood protection and UDP keep-alive values being related to this issue but I can't seem to find those posts anymore.
Things I've tried so far / more information about the issue:
(SIP Trunk) Changed reregistration period to 60 then 10 (currently default 120).
(SIP Trunk) Changed SIP transport protocol to 'All' (currently default UDP).
(PBX) Disable Windows Defender Firewall.
This happens on deskphones and the app.
Internal calls are not affected.
Inbound calls not affected.
Internal calls do not make outbound calls resume.
When working, outbound calls have no issues
Phone message gives 'Temporarily Unavailable' (Yealink T30P)
The time period between outbound calls working and not working is probably around 5-10 minutes although I can't measure this exactly.
Concurrent call limits not an issue.
Any advice on what to do from here much appreciated as I don't know where to go from here. Bonus points if anyone has experience with this problem and this router!
Thanks
Dan
I'm a bit puzzled by this one. I'm 99% sure it's the firewall but exactly what is doing it I don't know.
As above, outbound calls only work after an inbound call has been made and this is only for a short window of time. The error in the event log for a failed call is:
"...has failed. 0.0.0.0 replied: 408 Request Timeout; internal"
I've done a Wireshark trace and examining the results for port 5060 shows that the INVITE is sent from the PBX to the SIP provider IP but nothing seems to come back/no ringing message ever gets sent. Speaking to the SIP trunk provider, they can't see anything on their end either so it would seem that everything stops at the router/firewall.
Additional setup info:
3CX Version: 18.0 update 2
Server OS: Windows 10 Pro
System is hosted on premises
Trunk provider: Gamma
The router/firewall is a Cisco Meraki MX85, The firewall check comes up as all passes except for SIP ALG which I'm told is normal for this router and it doesn't have the SIP ALG function. Unfortunately, I do not have control over this router and it's managed by a provider in a different timezone making life tricky meaning that implementing any changes can only be done in a short timeframe due to any changes also needing approval. I just need to know what to request or ask of them although I did ask them today if they could see what was happening to the invite messages coming from the PBX.
I remember seeing something about UDP flood protection and UDP keep-alive values being related to this issue but I can't seem to find those posts anymore.
Things I've tried so far / more information about the issue:
(SIP Trunk) Changed reregistration period to 60 then 10 (currently default 120).
(SIP Trunk) Changed SIP transport protocol to 'All' (currently default UDP).
(PBX) Disable Windows Defender Firewall.
This happens on deskphones and the app.
Internal calls are not affected.
Inbound calls not affected.
Internal calls do not make outbound calls resume.
When working, outbound calls have no issues
Phone message gives 'Temporarily Unavailable' (Yealink T30P)
The time period between outbound calls working and not working is probably around 5-10 minutes although I can't measure this exactly.
Concurrent call limits not an issue.
Any advice on what to do from here much appreciated as I don't know where to go from here. Bonus points if anyone has experience with this problem and this router!
Thanks
Dan
