Sending sms from Rocket Chat

Overview: We sell a service "TextOurCompany.com" that enables businesses to text enable their existing business numbers. Our underlying carrier is Twilio. We are using RocketChat's Livechat and Twilio integration to give our clients the ability to receive and respond to sms messages. We wish to also give them the ability to send NEW unsolicited sms messages - not in response to an incoming message.

Description: We would like a page - probably under LiveChat that has three fields: From, To, and Message. Following is a description of each:

From: This will be a telephone number that the message is from. This must be a valid number that is on the client's Twilio subaccount.. There could be more than one number. So, this could be a variable entered elsewhere and offered as a drop-down.

To: The user enters one number or multiple numbers that the text message will be sent to. The user can either enter multiple numbers separated by a comma, or possibly upload a csv file of numbers to send to.

Message: User entered information. Should be at least 4 x 164 characters in possible length. Perhaps a note somewhere that says "Messages over 164 characters may be send, but will be counted as multiple messages"

I think that is it for now.
~John

The issue names no files, tests, or entry points. Start by locating the existing Livechat/Twilio integration and its UI and server paths, then determine how outbound messages and Twilio numbers are represented. Done would require an agreed design covering sender selection, multiple recipients or CSV input, message limits, and validation.