can you send to other carriers besides t-mobile? check your picture resolutions. some carriers will not transport pictures above a certain size, and it won't give you an error, just reject it at the gateway. cricket does not do this (supposedly). to my knowledge verizon was the only one doing this, but it is possible t-mobile does too. like you said, one t-mobile works fine both ways, the other only works one way. i'd focus on trying to figure out what the difference is between you those two specific cases.