Block T.38

sympology · Post by **sympology** » Mon Sep 22, 2014 6:03 am

1. Brekeke Product Name and Version:
Advanced 3.3.3.1

2. Java version:
1.7.0_15

3. OS type and the version:
W2008

4. UA (phone), gateway or other hardware/software involved:

N/A

5. Your problem:

Is it possible to block T.38 negotiation via the dial plan? I know how to allow the likes of G711a G11u, 101 only but can't work out T.38 as it's as far as I know not a standard Payload as such.

Thanks for any help.

Ericcc · Post by **Ericcc** » Mon Sep 22, 2014 9:39 am

Try this. It rejects T.38 request with "603 Decline".

Matching Patterns:
$request = ^INVITE
$body("^m.+t38") = .+

Deploy Patterns:
$response = 603

sympology · Post by **sympology** » Tue Sep 23, 2014 2:24 am

Ericcc wrote:Try this. It rejects T.38 request with "603 Decline".

Matching Patterns:
$request = ^INVITE
$body("^m.+t38") = .+

Deploy Patterns:
$response = 603

Thanks I'll give this a go and let you know how it goes...

sympology · Post by **sympology** » Wed Oct 01, 2014 8:34 am

A bit of messing around, looking up and wiresharking and it occurred to me this won't work as is.
The issue the t.38 is not sent in the initial set-up of the call, but in a re-invite.
So the call flow is (basically)
SIP Invite > OK > RTP > RE-INVITE > t.38

So I presume I can do a reinvite interception instead of a invite, but got to sort out a clean way of doing this.
I'll update if I can work it out.