Verizon Wireless LTE/4G and SIP Header Manipulation

Mailman List Mirror (Read Only)
1

Hi All,

Has anyone seen that something (most likely an alg) on Verizon's LTE/4G network is rewriting SIP headers,in particular From Tag identifiers? We cannot make a SIP call from our cellphones (using cellular data) beyond 30 seconds because the TAGs are rewritten and the destination Asterisk server drops the call because of this.

Thanks

Mark

2

Hi All,

Has anyone seen that something (most likely an alg) on Verizon's LTE/4G
network is rewriting SIP headers,in particular From Tag identifiers? We
cannot make a SIP call from our cellphones (using cellular data) beyond 30
seconds because the TAGs are rewritten and the destination Asterisk server
drops the call because of this.

I'm shocked that the cellular carrier is making over-the-top phone
calls non-functional. I'm sure they'll agree to meet you at their CO
so you can do the proper work request sometime between 6am and 7pm in
2 weeks time.

go incombancy!

3

Hi All,

Has anyone seen that something (most likely an alg) on Verizon's LTE/4G
network is rewriting SIP headers,in particular From Tag identifiers? We
cannot make a SIP call from our cellphones (using cellular data) beyond
30 seconds because the TAGs are rewritten and the destination Asterisk
server drops the call because of this.

sounds like a really good application for TLS

4

TLS would be perfect but it is not viable at this point. I guess with Verizon being what they are, it is time to start working on a SIP over TLS implementation.

5

Send all of your signaling over TLS and they won't be able to see or modify it.

Steven Naslund
Chicago IL

6

Hi All,

Has anyone seen that something (most likely an alg) on Verizon's LTE/4G
network is rewriting SIP headers,in particular From Tag identifiers? We
cannot make a SIP call from our cellphones (using cellular data) beyond 30
seconds because the TAGs are rewritten and the destination Asterisk server
drops the call because of this.

I'm shocked that the cellular carrier is making over-the-top phone
calls non-functional. I'm sure they'll agree to meet you at their CO
so you can do the proper work request sometime between 6am and 7pm in
2 weeks time.

joking aside, are you sure the packets get mangledin VZW and not
elsewhere along the path? how would you be able to prove it?

7

I've seen this behavior before (a few years back). Moved off of VzW for
this reason (i'm lazy to implement workarounds).

IIRC when i investigated, the ALG was trying to not do something nefarious
but just poorly implemented.

8

The TAG unique identifier is being changed and this only happens through VZ LTE networks, not wired networks or even other cellular data networks (Sprint, ATT, T-Mobile)
Their phones are IPV6 so the packets are getting converted to IPV4 so it is either happening there or there is a global ALG in Verizon land that is doing it .
For positive proof I would need Verizon to fess up (LOL) but that will not happen or sniff traffic from the cellphone itself.

9

welp, interesting, good luck in your battle with the pstn.

10

I’ll say it’s not just VZW that does this, there are issues with many CPE devices
that mangle SIP traffic due to broken ALG. My plea is if you’re a carrier
that provides a CPE, *please* provide an option to disable the ALG, or expose it
to the customer so they can disable it. *Looks in 7018/7132 direction*

- Jared