Some Texts Not Sent/Received

I'm not sure if this is the best place to have this question, so if it's not I'm sorry. Anyway I have Verizon as my provider and my girlfriend has AT&T. We text pretty frequently but every few days she won't receive my text for a very long time, if she even gets them at all. Sometimes I don't get her texts until hours after she actually sent them.

We've been texting for months now but I just started having this problem a few weeks ago. Do you think it's because we have different providers or could it be my phone?

ive a feeling it has something to do with having to go from one server to another (the stuff is in effect an email transmission) they may be improperly routed between the two services as a possibility.

it could be your phone, however I would recommend you both contact each carriers technical support department and have a trouble ticket open that way both sides can research it to see if its on either side.