If a friend sends you a text message from an international number, and you have an incorrect number for them in your contacts list you may receive an error when trying to reply to their message.  If the error message say ‘15555… number is incorrect (or something to that effect)’ you should create a new contact entry on your phone with the correct phone number.  Recently I encountered this issue on an Android device and no matter how many times I tried to correct the phone number for the original contact entry, it would not save correctly.

So what caused the text message error in the first place when I was simply replying to a text message from an international contact?  Maybe it is an encoding issue with the phone number coming from an Apple device to an Android device or due to either the phone carrier simplifying the phone number.  In short, when you receive an international text message, the ‘reply-to’ phone number sent to your phone may be incorrect.

To fix the issue I create a new contact entry for the friend on my phone and entered the correct phone number (ensuring it has the correct phone prefix characters, such as ‘+’ where required).  I then sent a text message to the new contact entry and was able to get the text message to go through.  From there I was able to reply to text messages from the contact without issue.