After updated iPhone4 to iOS 5 I cannot text some people. Receive an error message. Have backed up and done a restore. Deleted the particular contacts and re-entered the valid 10 digit number. Any help???

What is the error message?

I'm having the same issue.

The message is: "2639209 Error Invalid Number. Please re-send using a valid 10 digit mobile number or valid short code."

So it makes it real hard to respond to someone as the number they are texting from doesn't have all 10 digits. So I end up having to send a message using their phone number that has the 10 digits.

This only started happening after the iOS5 update.

I am having the same issue!!! Have tried to adding a 1 in front of number and it still doesnt work. I am just replying to people on AT&T and they have iPhones too. The contact info has been a 10 digit number from the beginning.

I have found a way to text back but it is frustrating and I should not have to do it. I scroll to the top of message page, select contact, then select send message.

Yeah thats what I say every time i have to reply to certain people.....

Frustrated and dont know what to do!!!!!!!!!

I am having the EXACT same issue! I get the error message and I am using a 10 digit number! UGH! I have spent hours on the phone with APPLE CARE, restoring the phone to its original factory settings worked but what am I suppoed to do....restore every time I wanna send a text to these few people in my contacts?? UGH!!

If you are responding to other iPhone users, is it actually a text message or an iMessage?

Is the bubble green (SMS) or blue (iMessage)?