[SIPForum-discussion] SIP trunking. Use of payload type 13, 97 and 98

[juanof at vtr.net]

Hi to all,
             Please if anybody could help me to understand, what could be the 
reason for restriction of use of payload types 13, 97 and 98 in SIP message 
body, media description.

I'm trying to make GW calls through SIP trunk, but NGN demands to me, not to 
use these payload types. Any idea to require this?.

Thanks in advance for any help.
  
Best regards,

Juan Ordenes.