Web services and mobile devices consume

Based on the suggestion provided here - [http://ift.tt/1agvziH], posting the query again here

I need to write an app, which targets all the mobile platform available currently (Windows Phone, iOS, Android). The application requirements are as follows.

1. Hosted web service/WCF service which process request and returns the result back to requester.


2. The devices can raise request and show the result received by services


3. There is also notification feature where is if the user has subscribed to a specific service they will get notifications on their mobile devices

The application quite simple, but not sure how to go about. I would like to start of with Windows Phone as I am more comfortable with windows at present.

The system I am planning to use is as follows

1. Windows Server 2012 R2 with IIS enabled for hosting services (public domain)


2. SQL Server 2008 R2 database (soon moving to SQL Server 2012)


3. C# as programming language for at present windows phone application development


4. The application is also targets for Windows Store application where they can download the app on their desktop application for their use (future dev)


5. This is also an Web Application where the user can login and use the services.

How to go about with this?

Thanks in advance!!!