Using two ISPs. One is okay, other has delays and incomplete target route?

[David Fowler]

We have two ISPs (dual WAN) that we use within the office. Connecting to a hosted 3CX server with STUN. The slower ISP handles calls in a timely manner (but vanishes since last upgrade, subject for another time), the faster ISP adds 10-15 second delay to calls.

Sticky particulars:

3CX 16.0.3.676
Debian 9 at OVH
Yealink T48S(15), T40G(1), CP960(1)
All set to STUN
Trunk is VoxTeleSys (nice people) uses registration/account based
Passes Firewall check
No custom telephone templates

While scouring the logs with the log reader, I did find this interesting tidbit?

On the working ISP, the target route for CM503004 and onward has a target route twice as long as the annoying ISP.

Good: T:Extn: ext#@[Dev:sip:ext#@ispgoodip:47870,Dev:sip:ext#@127.0.0.1:5483;rinstance=hexgobbledigook]

Delayed: T:Extn: ext#@[Dev:sip:ext#@ispdelayedip:28868]

The second sequence with the localhost and rinstance is missing? Is this a clue or a red herring?

Cell phone apps don't appear to care which ISP is used, they just work. I don't mind barking at the ISP, but I would like to be coherent? Or I can kick myself if it is something on my end.

 

[Evolute IT]

We have two ISPs (dual WAN) that we use within the office. Connecting to a hosted 3CX server with STUN. The slower ISP handles calls in a timely manner (but vanishes since last upgrade, subject for another time), the faster ISP adds 10-15 second delay to calls.

Sticky particulars:

3CX 16.0.3.676
Debian 9 at OVH
Yealink T48S(15), T40G(1), CP960(1)
All set to STUN
Trunk is VoxTeleSys (nice people) uses registration/account based
Passes Firewall check
No custom telephone templates

While scouring the logs with the log reader, I did find this interesting tidbit?

On the working ISP, the target route for CM503004 and onward has a target route twice as long as the annoying ISP.

Good: T:Extn: ext#@[Dev:sip:ext#@ispgoodip:47870,Dev:sip:ext#@127.0.0.1:5483;rinstance=hexgobbledigook]

Delayed: T:Extn: ext#@[Dev:sip:ext#@ispdelayedip:28868]

The second sequence with the localhost and rinstance is missing? Is this a clue or a red herring?

Cell phone apps don't appear to care which ISP is used, they just work. I don't mind barking at the ISP, but I would like to be coherent? Or I can kick myself if it is something on my end.

Does this only happens with deskphones? If so, have you checked your firewall ports forwarding? You are using 3 phones in STUN which is pretty much the limit (unless they are not on the same network).

Also, I'd run a packet capture from 3CX on both scenarios to compare what steps is slowing the call down.

 

[JohnS_3CX]

Hi David,

Regarding the dual WAN, are you using one at a time or can a phone connect to the PBX from either? How is NATting handled?

Since you have more than a handful of phones, I would suggest to consider installing an SBC to bypass any firewall related issues and perhaps some ISP based issues too (depending on the case).