I can't text to certain numbers that I need to

[AC Question]

I while back I was sending a text to a number like 43433 for example and I pressed remember my choice but acicendaly clicked don't allow. How do I change this so I can text numbers like this

 

[B. Diddy]

Welcome to Android Central! Which phone? Look in the Phone app's settings to see if there's an option to enable Short Code SMS.