MiCollab registration fail loop on some WiFi networks

[rsh_mitel]

I have a rally tricky issue
MiCollab on IOS, v 9.3.111
Server 9.3.0.30
it works fine on some WiFi networks but goes into registration fail loop on other
Can't seem to find any difference between those wifis, some of them are out of the box verizon FIOS so can't be that different.
My integration vendor is having hard time figuring this one out despite diags sent many times over
Anything you could suggest me to try?
Factory reset, SIP pwd change was done many times over already

Thanks

[dilkie]

f/w rule somewhere...

You'll need to get network traces to confirm. SIP is a known protocol and sometimes there are SIP ALG (Application Level Gateway) logic that tries to "fix up" sip messaging but usually ends up messing it up.

If you can, turn off any SIP ALG's. Also, using sip-tls rather than udp can help because the traffic will not be observable to any f/w code and thus avoid modification.

[rsh_mitel]

Thank you for your advice

Looks like disabling SIP ALG on Verizon FIOS routers is off the table for most users
https://kb.intermedia.net/article/3343

On my server settings I have SIP set to use all 3 protocols, UDP, TCL and TCP/TLS. Are you aware of a way to force MiCollab app to use TCP/TLS only?

[dilkie]

assuming you are using an MBG, configure sip with udp only on the "private" side if you don't have any udp sip trunks. or disable udp sip altogether if you have sip tcp or tls to your icp.

[johnp]

I think tls is default unless changed

[Dogbreath]

SIP TLS precludes any "help" from SIP ALGs!