SMS Messaging Apps

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A single SMS message is limited to 160 characters so how can larger messages be sent?

Standard SMS Apps on the phone. Every phone will have an SMS App which is used to send SMS messages. If the message is longer than the 160 character limit the App will split the message and send using the Long or Concatenated SMS protocol. If the user tries to introduce multi-media into the message the default app will use the MMS protocols to send the data.

When receiving an SMS message, the App will try to be helpful to the recipient by highlighting links, emails, phone numbers making them clickable. This is done within the App without actual links in the SMS message. As an alternative to SMS there are a number of messaging applications for which Whatsapp is the most popular. This is build in a similar manner to the older chat systems using the XMPP protocol. The user is presented with a screen not disimilar to an SMS app where they choose recipients, add text and multimedia. The message is sent to one of a number of servers. Whereas SMS, and it's derivatives work over the phone system, the contriol channel, Whatsapp uses HTML5 Web Sockets. The WebSocket send() method is used to send the message. The onmessage() method is used by a user to see if there is any messages for them and if so these are downloaded. Note that Whatsapp and other App based messaging systems use Data sevices HTTPS and the Internet and not the telephony control system that SMS uses.