Here’s The Fix if You Cannot Send Out SMS on iPhone 4S, 4 or 3GS

First of all, you need to check your SMS center number to make sure that it’s correct. You can check by typing the following and press Call:

*#5005*7672#

You will then get the message as shown below:

Setting Interrogation Succeeded
Service Center Address
+8613800100500



To Add T-Mobile Service center for Messaging:
(iphone 4/4s)

**5005*7672*+12063130004#

T-Mobile Center: +12063130004