3CX server on failover 4G connection with private IP address

[agentsmithitaly]

Hi to all,
I have a local 3CX server on company premises connecting to SIP trunk over an Internet connection with static, public IP address via a Draytek Vigor 2120 router.
All extensions points to local IP address of 3CX server except if they are external.
Said router supports failover 3G/4G connection using a USB Internet key.
But 4G connection only provide dynamic, private IP address.

Does 3CX work on such a connection? All I have to is to enable "Dynamic Public IP (IP changes)" in Network Settings, correct?

What happens to external 3CX client such as Android apps? Will they simply re-register on new server IP address when 3CX FQDN DNS record is updated?

 

[Saqqara]

Just set the system to use 'Dynamic Public IP' , but be aware if not using Enterprise version of 3CX it can take 6hrs for the dns to be updated (this is the TTL)

 

[agentsmithitaly]

Thank you for the quick reply.
This 6hrs DNS update delay shouldn't impact communication with the SIP trunk, am I right?
Through STUN it should update the IP address quickly, so only external clients would be impacted by the DNS delay.

 

[freshEF]

Be careful with LTE backup.
We had 3CX installed at one of our branch offices, with static ip cable, and a failover with static ip verizon lte. It was a horrible experience.
So bad, that we ended up just static routing 3cx traffic on primary because verizon messes with SIP traffic.(they claim otherwise)
Once we moved our 3cx to the cloud and used an sbc it works surprisingly well over lte (imagine that)

 

[agentsmithitaly]

Thank you for your insights!
I had bad experience with 3CX on the cloud, though it may have been affected by substandard router and low upload bandwidth.
I will give it a try and let you know my findings.

 

[freshEF]

If the phones you have support it, the SBC is Magic. No port forwarding needed, let your router handle the failover. It just works. I like just works.