Do I have to choose SMS receipt?

No, the SMS receipt is not something you have to choose, this is optional.

This is only an extra service we provide if you want your order confirmation on SMS and not only on e-mail. You'll always get the order confirmation by email, but now you have the option to get it on SMS too.

NOTE: most organisers do not accept the SMS receipt as a valid ticket confirmation, as the SMS receipt is for personal bookkeeping only.