My iphone is not letting me send pictures all of a sudden?

I sent a few pictures today and tonight it's not working. I attach it to a text message and it says message failed. I tried restarting my phone, making sure the SMS is enabled and also doing a software update. Btw it's an iPhone 4 with telus.

Is service poor where you live?

in my home for example, certain areas of the house is crap leading to texts not being sent etc.

When i had this problem, it was because i had cellular off. I turned it on, and everything was fine.