I only sign up for wireless communities when their gateways are broken.
As such, I have accounts on all of them aside from Sprint. Props to Sprint for not letting monkeys run their networking equipment.
Current Adventures:
T-Mobile: Blocked messages forwarded from one tmomail.net account to another via the SMS gateway, thinking they were spoofed (despite containing THEIR message ID and all headers, unmodified). Took a month to fix, but eventually they DID fix the error, which is awesome. Go TMO.
AT&T: Dropping messages sent via the SMS gateway, but only to users in San Jose, CA (???). Support refused to help, claiming since I was the sender, I wasn't actually the affected party, and they wouldn't look into the issue unless one of the intended recipients requested it. I CC'ed one of said recipients into the email chain, and support went dead. 10 days of dead air so far (as of March 8th). Now bounce messages are coming in claiming "<xxxxxxxxxx@txt.att.net> Recipient does not exist here", despite assurances from the recipient that he most definitely does exist (AT&T lying? No way!). Scumbag behavior at its worst.
Verizon: the vzwpix.com gateway sends all replies to the BOUNCE ADDRESS of the original email, while ignoring all other headers (From, Sender, Reply-To). It is impossible to have the reply NOT end up in the bounce mailbox. Meanwhile, vtext.com behaves as it should (How does that even happen).
Sprint: Still being awesome, still not letting children tamper with the SMS gateway, still functioning. Hooray!