Contact (SIP) and 'Connection' (SDP) Settings

[Customer-3CX]

Hi,

Setting up a Generic SIP Trunk and having unexpected results with the Contact URI Host Part in the SIP Invite.

Then under the Outbound Parameters tab, have configured the;
"Contact: Host Part" to: "ContactUri" usually, content of Contact field

Under the SIP Trunk | Options tab, have configured the;
"Select which IP to use in 'Contact (SIP) and 'Connection' (SPD) fields" to:
'Local IP Address (OS Default Route)'

So from my readings, i thought the following options would present the following results:
"Select which IP to use in 'Contact (SIP) and 'Connection' (SPD) fields" to:

• 'Use Default Settings' --> Would utilise the Public IP Address
• 'Local IP Address (OS Default Route)' --> Would utilise the local NIC's IP Address
• 'Use this IP Address' --> Would utilise the listed IP Address

But in the outbound SIP Invite packet, I am seeing the NAT'd Public IP Address of the 3CX Instance.

I have seen other posts referencing an additional check where if the local IP Address is within the RFC1918 ranges and the destination IP Address is in the Public range, then 3CX would still utilise the confiugred Public IP Address, is this correct?

The issue we face selecting the defined IP Address option, is that we have configured our 3CX environment in an Active/Passive failover, and the restore of the Primary instance's configuration back would set the wrong IP Address in the Secondary instance. Therefore a manual intervention would still be required in a failover scenario, which is not optimum.

Thanks in Advance.

 

[eddv123]

This is a perfect example of why to use a 3CX supported SIP trunking provider, all this work is already configured in the template provided in the system.

Despite this I hope this guide may give you some help, have a read: https://www.3cx.com/docs/sip-trunk-registration-authentication/

 

[Customer-3CX]

This is a perfect example of why to use a 3CX supported SIP trunking provider, all this work is already configured in the template provided in the system.

Despite this I hope this guide may give you some help, have a read: https://www.3cx.com/docs/sip-trunk-registration-authentication/

Thanks for your response eddv123.

Regardless of selecting a 3CX supported SIP trunk provider vs a Generic Sip Trunk, the issue is only seen during a Failover scenario, as the secondary server is in a different geolocation which has a different network segment. Both the Primary & Secondary locations have routable access to the SIP trunk providers endpoint via MPLS.

My query is based on anybody else experiencing the same issue when selecting the "Local IP Address" option. Is this a bug, or am I interpreting these option incorrectly.

 

[eddv123]

I have in fact setup failover but have when it was single licence (not enterprise) it was a real nightmare but at the time used SIP trunking from VoIP unlimited who at the time had a template. I may do some further testing and if I come up with anything report back.

 

[YiannisH_3CX]

Hello @Customer-3CX

The option you refer to will add the local IP to the contact header if the destination of the Register / Invite is local. If the destination is not local the public IP will be added instead.

 

[Customer-3CX]

Thank you for your response YiannisH_3CX.

Are we able to submit a Feature request to have an option not to override the local IP Address when the terminating SIP endpoint is in the Pubic assigned ranges?

We see the current scenario as a limiting factor in a Enterprise environment where seamless failover is required/preferred.

 

[YiannisH_3CX]

Please feel free to submit this as a feature request in our Ideas section of the forum. https://www.3cx.com/community/forums/3cx-ideas/ . All posts are reviewed by their corresponding Departments and, if feasible and voted for by other users as well, may be implemented in an upcoming service pack or update.