Level 1: Cadet

SMS error code 21

I've never experienced this problem whilst sending my friends an SMS or a call, I have service, bought a new phone as a solution which didn't work and I know for a fact that my number hasn't been blocked. Please help.

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Level 25: The Singularity
Level 25: The Singularity

Re: SMS error code 21

An error code 21 on an SMS is usually because the number is entered wrong in the contacts list. It may be entered in internatioanl format and have the zero included (eg +61 0427 XXX XXX) when it should be without the zero (eg +61 427 XXX XXX).


Have you tried entering the number in directly when you are trying to send the sms?

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