I encourage you to comment on this issue if it happen to you and you have a better solution.
For a few months, maybe a year ago, is dropped as if by magic the phone number that is the center of Movistar SMS messages (or so I explained the technical service Movistar).
To reconfigure it I have to dial the following code:
** 5005 * 7672 * +34609090909 #
After I press the call button and an error message appears if the problem is fixed. SMS working again.
What you do not know is why it happens so often and why. Now I use other messaging services through the network rarely resort to the SMS, but when I do I almost always have to reset the message center.
Do you ever tried?