When an operators network is clogged, i.e. millions of data transactions are occuring at relativley the same time, your text it put into a kind of queuing system. this does not neccessarily work on a first come first serve basis. It can also work on a, which is easiest to deliver basis, if your message contains a large amount of data, (characters, pictures or sound) they will take longer to deliver. Usually most mobile network operators provide a speady delivery but in some cir***stances or times in the day it is understandible. Imagine your postman/woman on a Monday only has ten letters to deliver, it will probably take him/her about ten minutes dependant upon distance between delivery points. On Tuesday, he/she has 200 letters to deliver, this will take substantially longer to complete the round...... Hope this helps clarify....