Updating sip.conf.sample with information about T38 not working

when chan_local or chan_agent is involved in the call.

I don't know how big a fix that would be to solve, but this is
the current state of affairs.

(Chan_sip currently checks if the other side of the bridge
has a SIP tech. We could/should implement another check,
possibly for udptl_write or some flag in the ast_channel
structure).


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@48264 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configs/sip.conf.sample

@@ -209,6 +209,8 @@ srvlookup=yes			; Enable DNS SRV lookups on outbound calls
 ; This has to be enabled in the general section for all devices to work. You can then
 ; disable it on a per device basis. 
 ;
+; T.38 faxing only works in SIP to SIP calls, with no local or agent channel being used.
+;
 ; t38pt_udptl = yes            ; Default false
 ;
 ;----------------------------------------- OUTBOUND SIP REGISTRATIONS  ------------------------