i was using the 822 on straight talk with portico on it, i sent and received SMS, and i was able to send MMS, i had the APN settings wrong to be able and open received mms,
and i also have another 822 that was on pre portico and same, but since i have them with verizon, i did not dig deeper to get the right apn settings as i got them with the Lumia 920 working right.
I will check both phones again when i get back this weekend, but i also had to download Nokia app to access apn settings. on pre portico you can go to and edit mms and web, on portico the app had the option to add a new apn.
so just read around this forum and you will see direct links to download the access + app from market.
i got straight talk powered by ATT towers, and got a regular Tmobile prepaid account so i can check this weekend on both. and see if i copy the apn settings from the 922 and hope everything works.
edit: also when i upgraded one to portico the network+ or access plus or whatever that app is called it installed automatically, there was no need for me to download manually. one device was already updated to portico and other was on pre