I want to make it possible that my Oxwall can send sms notifications like it already does with emails!

It means, it must send sms when:

-the user registers and get the verify notification

-the user changes his number in his profile

-the user has forgotten his password

I already made those functions and they worked, but it was more like "tinkering" in the ow_system_plugins.. not really professional.

Now I want develope a plugin for that, but is a plugin the right thing for those tasks? 

For example: I added a new Profile Question: mobile_number. It is only showed on Join and on edit profile page. I want to add a Verify Button right to it. When the User changes his number, he can click on the VerifyButton to send a verify code per sms and be redirected to the verify mobile phone form page. Then he has to put in the recived code and verify his mobile phone. 

But for that the ow_system_plugins has to be edited or not? Can a Plugin do that?