Ok all the work is done through the BxDolTwilio.php class in inc directory. 

The sms is sent from in side this file.

 I was able to send sms through gatewayapi . com by using only 'to' and message (code) variables in the class like with the api token of gateway api. 

With my hack in 2 hours, it works but I didnt like the quality. And I dont want to reserve more time  for this cause i have big things to do and candidate members are waiting.

(But the code UNA wrote is very clean and well structured, it seems like they even prevented to happen multiple instances of the send sms event. )

We may ask UNA to implement a plugin also for gatewayapi to benefit from their good price level. (They can do it as power application also.) It will not take their time that much. I guess in the same day they may finish :)
By the way today in the afternoon at last Twilio answered saying that for Turkiye and some other countries it is needed to pre-register sender id .
Now i am waiting to learn it's cost and procedures.