Inbound SIP Redundancy Configuration Question

[jwood]

We are attempting the following...

We have 3 different ISP's and an IP-based (no registration) SIP trunk. Our SIP trunk provider attempts to send inbound calls to a public IP on ISP1. If the IP is unreachable, they move on to a public IP on ISP2. If it is unreachable, they move on to a public IP on ISP3.

When I manually put one of our ISP's out of service I see the following behavior...

The SIP trunk provider sends the call to ISP2 but the call fails. 3CX sends a "603 Decline" back to the SIP trunk provider that says:

Warning: 499 3CX1.ourdomain.local "Caller is forbidden"

Is what we are attempting to do possible?

 

[leejor]

How are you "switching" 3CX between the different ISPs? I assume that your public IP is changing when you change ISPs. I assume that you are able to receive calls when using ISP 1. Have you only created a single trunk group to handle this?

 

[cobaltit]

Registration-based trunk would likely solve your issues. Otherwise you'll want a SD-WAN product (we're a fan of BigLeaf) that will maintain your IP across multiple ISPs.

 

[jwood]

How are you "switching" 3CX between the different ISPs? I assume that your public IP is changing when you change ISPs. I assume that you are able to receive calls when using ISP 1. Have you only created a single trunk group to handle this?

Right. Our public IP does change when we switch between ISP's. I'm guessing that is part of the problem. Does the static IP in "Network Settings" have to match the public IP where the inbound SIP call request was received?

Registration-based trunk would likely solve your issues. Otherwise you'll want a SD-WAN product (we're a fan of BigLeaf) that will maintain your IP across multiple ISPs.

Thanks for the recommendation. I'm looking at BigLeaf now. Is this the solution you're talking about?

https://www.bigleaf.net/same-ip-address-failover/

 

[cobaltit]

That's the one. The same IP address failover is great for situations like these.