I can promise you that you dont need to change your IMEI.. You dont need to trick them with anything. You just need to get someone that knows what the hell they are doing. I simply called today to AT&T and advised that I need some help with picture messaging... I told them the truth that I had an iPhone and I found a way that I can send and receive MMS. i told them that i needed their help. I just advised them to access "SNOOPER" and enable MMS for me.. he did it and now it works like a charm.. the key is just being NICE!
mmsc: mmsc.cingular.com
Proxy: 066.209.011.032
apn: just leave it blank
username: just leave it blank
password: just leave it blank
to all you newbs.. do not type "just leave it blank" in the apn, username and password field... jesus..