Text problems with 5c

[Bunny T.]

I am having problems texting to some android phones. Does anyone else have this issue and what do I need to do to correct it. This is texting to friends in my same area code. I send to the area code and then number. Text is returned to me with the message "Message send using invalid number of digits. Please resend using 10 digit number or valid short code. Msg 2114".