Twilio like service

Hello guys I know that twilio is using this platform and I wanted to know if they have HEAVY recoded this application or is it relatively easy to do what they have done.

I but and I want to add the twilio function to all of my users accounts for no added costs. how difficult would it be to do what twilio has done. for those of you who don’t know what twilio does, they assign you a number and then a using and text your number and twilio will sent the data via POST to a web address. form that point you can store it in a database and display it how you would like.