Strawpay offers a Stroem solution for using 46elks' API for sending SMS. This makes it possible to use 46Elks API for sending sms:es and pay per message with bitcoin.
To use this you need Strawpay's Apiwallet and register for both a Strawpay account and a 46Elks account.

Resources

Apiwallet instructionsQuick start
Apiwallet zip downloadapiwallet-0.2.1.zip
Apiwallet docker imagestrawpay/apiwallet
Strawpay accountCreate account
46elks accountCreate account