Integrate SMS software allowing external SMS

I currently have software that is used to send out SMS messages. A "customer" can login to my service. They then create a list of people that they want to send an SMS out to in the future. From here they can type a message into our web based platform and hit send. This send the message out to everyone on their list. So as it stands the customer must be at a computer in order to send out a message. I want to give my customers the ability to send out an SMS even when they are not somewhere with internet. Can anyone develop an application that allows a customer to text a central number that then send the message out to their list of people. I would want some type f security to make sure that only the designated message sender could send a message to the group. The following is a good description of exactly what we do. I sell my service to soccer teams. The coach will use us to contact players and parents if for instance: game is cancelled due to rain etc.. The coach logs into our site. He will have his own account. On his account is the list of all phone numbers that he wants to send a message to. Then he enters his desired message into a field and presses send. The players&parents receive the alert. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). 4) I want to be able to to this on 5 accounts and then full payment will be made 5) Ensure full integration with my current software. ## Platform Web based software