Linkt to a Whatsapp-Chat runs fine on my website, but is it possible to link to a SMS Message (send a text message) on a mobile site?
Since the mobile number is used by the same provider phone and SMS this is not possible.
You could link to the phone number and automatically one gets linked to make a call (on desktop and mobile).
As there doesn`t come up an opportunity to write a short message there´s no way to do that, I´m afraid.
I just found out that it is possible, and as easy as it should be. Just changed "tel:+49xxx" to "sms:+49xxx" and it directly opens sms/text message window on android and iphone.