How do I fix the 'Out of range value adjusted for column' error?

I just changed the field type to BIGINT, and that fixed the problem. I guess i cant enter a value above 2147483647 for an INT, so I assume everyone who uses a field to enter a 10-digit phone number uses a BIGINT?

The value you were trying to set is too large for a signed INT field. The display width (15) does not affect the range of values that can be stored, only how the value is displayed.

Ref: MySQL Docs on numerics

On phone numbers - see Is it better to store telephone numbers in some canonical format or "as entered"?