Mobile Push Application - all brands of smartphone

Looking for a person or team to build a mobile app that will link to a database on the PC via push messages.
We will have a small team in an office. This app will need to be on all the time in the background on the mobiles, and when we send out the details we want too it will push to the phone.
the app also needs to have simple return values so the people can get back to us or a third party using Instant Messages (any), email, text or an in built sending function within the app (preferred choice) using several pre-set values from the outbound message and some user data.
We would also like GPS and Cell Tower location to be included in the app