1. Check the contact of the person for any linked contacts without phone numbers.
Open up the person’s contact and scroll to the bottom. If there are more than one contact that have similar information, your iPhone will link them together. It seems that after iOS 10 Siri is unable to navigate multiple linked contacts.
2. Add a phone number to the linked contact
2. Remove the linked contact if it’s a duplicate
Following these easy steps should solve your issue where Siri won’t text message people because she can’t find your number.
I hope this helps relieve some of your stress! Let me know if I need to add anything in the comments. ?