As I explained in this thread, text messaging serves different purposes than a phone call or email.
One you learn how to do it (only took me a few weeks) you can tap one out almost as fast as you can speak. I use full sentences and punctuation in my messages and I still think it is faster than calling in some situations. With auto-word fill-in and stored phrases I can type even long sentances in seconds.
It’s much less non-obtrusive than phoning. Let’s say I am out to lunch with a friend and my mom wants me to pick up some milk and bread at the store on my way home. If she calls, then I will not answer because I am with my friend. After meeting with my friend I would have to check my voice mail and if I got any other calls or have other messages in my inbox, that might take a while. If she sends me a text message I can check it in seconds and if I do it right, my friend won’t ever notice me checking the text messages.
I think it is less rude to send a text message than to call, say a short phrase and then hang up again. If you are late to meet your friend then (for me anyway) it takes less time to send a quick text message and you can do it while doing other things to get ready. Phone calls take longer and (I think) require more politeness which means more time spent.
They are great for situations where you want to send someone a note to let them know that you are thinking of them but don’t have the time for a phone call. On Christmas day as my brother was driving us to my Grandparent’s house, I sent a picture of our Christmas tree along with a text message wishing the recipient a Merry Christmas/Happy Holidays to ~15 people in my phone book. The friends were in a variety of different time zones and it would have been impossible to try and call each of them up to wish them merry Christmas, not to mention it would have been rude of me to do so while in the presence of my siblings. I was able to send several people a Christmas greeting while still conversing with the people I was with in person. What’s more, the people who received the greeting weren’t interrupted from their festivities for more than a few seconds, and that’s if they chose to check the messages then. About half of my friends list had similar ideas. Similarily, I love sending and getting little notes that say things like “Thinking of you” “I hope you have a nice day today.” which can be checked at the recipient’s leisure and don’t have the urgancy of a phone call.
Text messages also will go through sometimes when the grid is too busy. When I got lost in San Fran this October I couldn’t call any of my friends but I could text them.
I also have friends who send text messages from work. I know some of them aren’t allowed to do it and sneak it in (it’s easier to sneak in a text than a phone call) but others are permitted by their bosses to text, but not phone. Since my friend is at work where he/she can not call but still wants to carry on a conversation, I will text back instead of calling.
Text messages also eat up less battery life than calling. When I went to an outdoor music festival for a weekend, almost everyone there text messaged instead of calling because most of them needed their batteries to last them for three days.
And finally, as manx noted in that thread, for some people it is cheaper to text than call.