We're making this post, not because we need help with this issue, but because we've run into this issue a few times in the past few weeks are hoping to save others time and aggravation.
If your call is dropping exactly 30 seconds in, check the activity log for events with "ACK Not Received".
We've been there. Here are two examples of what we found.
First, run the firewall checker, and resolve any Full Cone NAT issues.
Don't bother support if your firewall is not configured properly first.
In both our cases, the firewall test was passing, and our issue continued to occur.
For our first customer, the dropped calls were intermittent.
Although the firewall configuration is a bit more complex than our usual install, the root cause of the issue ended up being simple.
If you have your SIP provider's IP range listed in your firewall, make sure that your white list is up to date. This issue was caused by a SIP provider that had added capacity and the new servers were not white-listed. This cost us a few hours on the phone with support before we found the resolution.
Adding those additional IPs to the white list solved the issue for us.
Another thing we found, troubleshooting the same issue type of dropped call issue for another customer, ended up being the wrong public IP address in the following field:
SIP Trunks => Edit => Options => [Select which IP to use in 'Contact' (SIP) and 'Connection'(SDP) fields] => [Use this IP Address].
The customer had changed Internet Providers, and the old Static IP from the old ISP was still in this field.
Correcting the IP address resolved the issue.
This prior post was also helpful in troubleshooting these issue. I would have added to it but it was closed.
https://www.3cx.com/community/threads/ack-is-not-received.62434/
If your call is dropping exactly 30 seconds in, check the activity log for events with "ACK Not Received".
We've been there. Here are two examples of what we found.
First, run the firewall checker, and resolve any Full Cone NAT issues.
Don't bother support if your firewall is not configured properly first.
In both our cases, the firewall test was passing, and our issue continued to occur.
For our first customer, the dropped calls were intermittent.
Although the firewall configuration is a bit more complex than our usual install, the root cause of the issue ended up being simple.
If you have your SIP provider's IP range listed in your firewall, make sure that your white list is up to date. This issue was caused by a SIP provider that had added capacity and the new servers were not white-listed. This cost us a few hours on the phone with support before we found the resolution.
Adding those additional IPs to the white list solved the issue for us.
Another thing we found, troubleshooting the same issue type of dropped call issue for another customer, ended up being the wrong public IP address in the following field:
SIP Trunks => Edit => Options => [Select which IP to use in 'Contact' (SIP) and 'Connection'(SDP) fields] => [Use this IP Address].
The customer had changed Internet Providers, and the old Static IP from the old ISP was still in this field.
Correcting the IP address resolved the issue.
This prior post was also helpful in troubleshooting these issue. I would have added to it but it was closed.
https://www.3cx.com/community/threads/ack-is-not-received.62434/
