Samsung Gravity TXT - receiving picture msgs

Hi all, this is my first time posting in the forums. Nice to meet you!

Without delving into details, I am in a situation where I have a Samsung Gravity txt and an unlimited texting and calling plan, while everyone else has iPhones. They have been sending group text messages to each other, of which I am included. I am not sure about the specifics of the mechanisms, since I have never used an iPhone before and I am new to cellphones in general. No one sends pictures with their texts, but my phone receives them as picture messages.

Yesterday, I received 10 messages in a short amount of time, and when I tried to access them my phone only said "downloading" for each of them. This downloading lasted for 50 minutes after the messages had already been sent. After this amount of time, I figured something surely had to be wrong, so I attempted to call a friend. My phone displayed three bars but said "emergency calls only" and that it was searching for a network. I restarted my phone, which usually works. I was able to call my friend, but unfortunately the message downloads all failed.

My question is whether this has something to do with the phone or whether it is a problem with the service. I checked my storage space, and I have enough storage for all of the messages I receive.

All help would be greatly appreciated!