Change/Add the google confirmation code in TC forum

[sudo]

Current TC forum is using Google confirmation code to recognize new user, but as we know, there is about over 1.5 billion people can not use Google service, that means about 1/4 or 1/5 people on the earth can not register TC forum and discuss their troubles, or suggest anything.

So I suggest TC forum to change the confirmation code supplier, or add a backup confirmation code supplier.

[ghisler(Author)]

change the confirmation code supplier

Do you know any?

add a backup confirmation code supplier.

Is that even possible?