I figured that was irrelevant seeing how it is carrier specific, but sure what I used being on Verizon, as I see you are too was...
Server Name= Verizon Wireless
Gateway= (nothing)
Port Number= 80
Server Address=
http://mms.vtext.com/servlets/mms
Connect Via= (Verizon Wireless should be here as long as it is set up in your connections, it should be selected already)