4701440 Error Invalid Number. Please re-send using a valid 10 digit mobile number or valid short code error message

Were you able to figure it out? I'm in the same exact boat. All the "solutions" don't work. I've NEVER been able to text my own BROTHER. He can send me a message no problem but the second I reply, I get the error response. This has been going on for about 5 years now, we hand both changed phones since, same problem. So annoying!

You have to do in this order:

Delete all messages with and from number

Delete full contact

Delete all phone calls with and from number

Reboot phone

Send message with 10 digit number and do not save contact until goes through.

I had the same problem and this method just solved it.

Best,

I have had this identical problem as well. I also just switched to AT&T a few weeks ago and had Verizon for a long time and have always had iPhones and never this problem. Have you solved this problem?

1. Delete all messages with the number.

2. Delete all calls with the number.

3. Delete the number from the contact.

4. Restart the iPhone.

5. Search the number in contact. Select “ignore” if Siri finds the number.

6. Now, you can create the contact with 10 digit number.

Since this an old question I assumed you probably had the issue corrected by now however, I wanted to respond in the event that my experience could help another Apple user. I too followed all of the steps recommended, on first attempt I received the same error message. Before I attempted for a second time I went to contacts, groups, unchecked iCloud and suggested contacts. After doing so I opened text message and typed in the number I wasn’t able to text previously, Voila! It worked!

What's to solve? That is not a valid 10 digit phone number...

try adding the sender to your address book and append the Area Code to the number

Just tried that, step by step.

Still does not work. I have never been so frustrated with something so simple in my life...

Oddly this seems to have worked for me. Problem just started a few days ago. Just switched to AT&T a few weeks ago. Had Verizon for over 10 years, always iPhones, and never had this before

This worked for me!

I have had the same thing happening when I text my sons phOne. Very frustrating and I didn't want to delete all of my old text messages or groups.

Same thing happens to my son when I text. Did you ever figure it out

Thanks formthe suggestion I have been super frustrated and didn't want to delet old text messages. Especially since I saw it didn't always worked. Thanks