Dear Sir,
I have read your requirement in detail and understand that a web/ Android app needs to be build, where in the web app will provide data storage of the Android App on a development server and involves functionalities like user ID creation and activation, allowing multi user ID, addition and removal of phone number.
On the other hand, the Android App it involves fetching of data from the server which is stored by the web app and fetches ID and storage, transferring the retrieved Phone Number to the native app for dialing.
However, if you have any detailed design document, it would be highly appreciated so that we could prepare a detailed requirement workflow. The web app will be coded using PHP or its allied frameworks and the Android app will be natively deployed using Eclipse as the IDE or any other Java based IDE.
Looking forward to working with you on this. We can chat via skype on sunnygoa1.
Cheers.