I wouldn't be annoyed as I prefer to talk to my friends.
Thats the trouble these days, people just text or e-mail rather than speak, also there's no emotions in a message..
If I think the conversation has finished then what's the point in replying? It p1sses me off more when someone texts you and it turns into a two hour textathon. It would be so much easier just to call me! Although sometimes texts are better, as you have proof!!! ;o)