So after doing some yahooing and alot of futsin around, I finally managed to get my MMS working by changing the settings. Here’s what to do:

Goto
Menu -> Settings -> Wireless Controls -> Mobile Networks -> Access Point Names -> T-Mobile US

Make sure you go into T-mobile US and not any other setting and change the name like I did, don’t even create a new one. It took me 2 months to figure out what I did wrong.

Change the settings to the following:
Name: T-Mobile US
APN: wap.voicestream.com
proxy: 216.155.165.050
port: 8080
Username: not set (delete everything in this field)
Password: not set (delete all here too)
Server: not set (delete the *)
MMSC: http://mms.msg.eng.t-mobile.com/mms/wapenc
MMS Proxy: 216.155.165.050
MMS Port: 8080
MMC: 310
MNC: 260
APN type: not set

Restart your phone. Now your MMS should work. If you have the 5.99 t-zones, I think your internet will work too. (UPDATE- it does work. check here)

[digg=http://digg.com/gadgets/How_To_MMS_picture_messaging_on_Tmobile_G1_without_data_plan]

*Troubleshooting*
1. If you’re having trouble still, go into mobile networks and enable ‘data roaming’ and ‘use only 2G’

2. Make sure your connecting to T-mobile US
-to do this go to the marketplace and download ‘any cut’
-open any cut and click create shortcut
-goto activity and select ‘testing’
-you should have a shortcut on your desktop that says testing, unless your desktop was full.
-click testing -> goto phone info -> this should tell you what connection you are connecting/connected to.
-For some reason if you are not using T-mobile US, change the settings for the appropriate one.
-If phone info shows you are not connected, hit menu and click on more and click enable data.
-now data should be connected.

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sorry guys, I haven’t been keeping up with this topic. Honestly, I don’t ever receive MMS. And If its that important, you can add on the $25 package once every few days, download all your mms the same day and take it off.
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G1 mirror screen protector

UPDATE*- These settings work for iPhone on T-mobile, maybe they might work on the Android:

Data:
APN: web.omwtoday.com
(no user name, no password)

MMS:
APN: web.omwtoday.com
(no user name, no password)
MMSC: http://wirelessfour.mmsmvno.com/mms/wapenc
MMS Proxy: 216.155.165.50:8080
Max msg size: 1058576
MMS UA PROF URL: (none)