what do you mean by NATTING? Im quite new to SER and SIP. Ive been researching this for a while now and have learned lots about it but am confused about a few things and now trying to put all the bits and pieces together. From what I know there are a few different types of NAT of which Full-cone NAT is the easiest to get through and symmetric NAT is not possible to get through without any reconfiguration of the NAT box. STUN can be used to help in NAT traversal and its quite successful and can achieve a success rate of about 80-90%. In other cases either reconfiguration of the NAT box is required or SIP clients will have to go through a media proxy. Now if I use mediaproxy with SER then will it proxy ONLY in the 10-20% cases ie when STUN fails? How will the SIP clients have to be configured if the server is running SER with mediaproxy and STUN is also running? Is the example config correct? sip proxy : sip.examplesip.com domain/realm : sip.examplesip.com NAT enable, STUN server :stun.examplesip.com username : sip_user password : sip_password outbound proxy : enabled. Should the SIP proxy address be same as SER's address or the server where mediaproxy is running? Should outbound proxy be enabled? Is it required to enable STUN in the SIP Client? Finally I would like to know if its possible to restrict some users to allow/disallow them to use mediaproxy. i.e. if they are not allowed to use my mediaproxy then they will have to open up the ports on their router to make calls. Thanks and would appreciate your feedback. Vikash. At 20:17 01-09-2005, Iqbal wrote: