Instant Messaging App Mechanism

Question

I've read many inconclusive articles regarding the mechanisms used by IM apps for mobile devices and I'd like someone to please clarify this for me. Do all IM apps for mobile devices simply use SMS? If not, how does the real-time communication between devices work? Is there an intermediate server? Thanks.

Answer 1

Most cellular carriers do not allow sockets which accept connections (servers) to run on mobile devices. As far as I understand, IM services with large numbers of users (eg MSN, AIM, Yahoo, ICQ, Skype) rely on a server to transfer the messages between mobile clients. I make this conclusion because each client must log into the server in order to use the IM service; they offer no way to do peer-to-peer connections and avoid logging in to the server.

Answer 2

No, SMS is never used for what's considered instant messaging by most. If you want to develop instant messaging app, you'll need a server and push notifications. I recommend Parse Push , but you should take a look at Google Cloud Messaging , too. If nothing else, it will give you an idea on how this stuff works.