From the research I did, and poking around in Swirly, this is the url swirly used for Nokia N95 user agent. And it worked on swirly to get big pictures from T-mobile MMS servers. I've also used different user agents on Symbian phones (e90 for example) to get larger sized picture messages. I've used the Nokia N95 user agent because I know it works. It works on Swirly2 and T-mobile USA and it also worked on my Nokia E90 using Yapn an T-mobile USA. Both results gave me big images from the T-mobile MMS server.. This is NOT the case on the iPhone.

http://<b>http://nds1.nds.nokia.com/...-1r100.xml</b>

BUT I didn't see ANY change in image quality of received MMS pictures.