Android/iPhone one-way Broadcast App to link up with a Joomla Website

We wish to integrate an iPhone and Android app into a Joomla website/service that we currently use to broadcast alerts out to our users. For now we primarily deliver alerts by SMS Text Message, and we wish to replace this channel in some cases by contacting our members for free through a web channel similar to WhatsApp messaging. If a user has installed our app then we will contact through the app instead of SMS. If a broadcast alert is delivered to the app and it does not trigger back a "Delivered" receipt within 3 minutes then we will assume they have no web access and therefore the original alert is followed up by SMS. The complete project overview is attached. We are not iPhone or Android developers so we are looking to work with a developer or a team of developers who can bring this project to life for us. We insist on fluent English speakers for this project. If the standard of English included on the proposal comes across as "broken English" then we will immediately disqualify the proposal. Submissions will be immediately disqualified if they simply include a generic response with a long general portfolio list. We want your proposal to be focused on the job at hand, with your portfolio apps/sites to include features that are part of this project spec. When you are bidding, please provide a detailed description rather than a brief summary. Also please include a proposed price. Please provide an accurate proposal for when you can start this alert and how long it will take to complete. We want to know how you can make this happen for us and we will determine with some advice if you fit the bill for this project. We expect this to work with older versions of Android (V3.2) and iPhone (iPhone 4) so that all potential users can make use of the App. We see this as V1 of the App, and we will eventually need a range of other features included. For this reason you should bid on this project with the view that if you are successful and we are satisfied with the finished product then we will be looking to work with you for a variety of future/similar products. We also expect that there will be an initial period of technical support after we test the app so we can ensure all bugs are teased out. We acknowledge that you cannot guarantee the app will be passed through the iTunes and Play stores, but we would like guidance in this area as part of the project fee.