stores the template for subsequent access during the session request process server sip processing function 35 then sends a set template message 80 to the server sip template processing function 40 for storage server sip template processing function 40 then responds with an ok message 82 to server sip processing function 35 server sip processing function 35 then responds with an ok acknowledgment message 84 to the client 39 s sip processing function 15 lastly client sip processing function 15 responds to the client sip application 10 with ok acknowledgment message 86 at this point the client sip application 10 has successfully installed a template for later use by the server the template can be changed at each registration process as shown in fig2 although the template need not be changed on each registration the extensions to the sip standard can be incorporated with the need to update both the client mobile unit subscriber or the network infrastructure turning now to fig3 the message compression procedure is shown for purposes of illustration a sip invite message will be used as an example however this process may be applied to any of the system or application messages transmitted client sip application 10 prepares and transmits the sip invite message header 100 to the client sip processing function 15 client sip processing function 15 determines that compression of this message is required client sip processing function 15 then transmits the sip invite message 102 to client sip template processing function 20 client sip template processing function 20 then compresses the sip invite header into a sip invite template 104 and transmits the template to client sip processing function 15 client sip processing function 15 then transmits the sip invite template 106 through client transport 25 link 50 and.