How do these SMS apps work?

Discussion in 'iOS Apps' started by yalag, Nov 18, 2009.

  1. yalag macrumors 65816

    Nov 18, 2007
    I understand the sending part, the apps probably fire off an email to the carriers and that sends as SMS. But how do they receive SMS?
  2. tctony macrumors 6502a


    Jun 15, 2009
    I'm pretty sure the people you send it to just receive it as a plain old SMS.
  3. yalag thread starter macrumors 65816

    Nov 18, 2007
    right, but how do the apps receive the SMS sent back?
  4. kicko macrumors 65816

    Aug 26, 2008
    the apps give you your own name@address that your friends can send to.
  5. yalag thread starter macrumors 65816

    Nov 18, 2007
    then how do my friends reply? doesn't make sense. do these apps actually let me SMS with my friends?
  6. kicko macrumors 65816

    Aug 26, 2008

    if you send a text from the app all your friends have to do is reply back. If they want to text you and not reply to one you have already sent from the app then they simple send it to your address
  7. trainguy77 macrumors 68040

    Nov 13, 2003
    Your missing the part that you can SMS to a email address. This allows them to reply to your texts which go the the SMS apps servers and are then passed on to you.
  8. yalag thread starter macrumors 65816

    Nov 18, 2007
    but this doesn't make sense. You are saying my friend can jsut reply back to the SMS I send him, and the reply will magically show up in my app? How can this be? The apps have some kind of ability to intercept SMS sent to my phone?
  9. IronLogik macrumors 6502

    Jun 15, 2009

    You send a message from the app. It includes all the information needed to respond to that message should they choose to reply. If they do, it's replied to and sent to the applications server. Which is then sent to your phone via the application you're using.

    Don't worry about how it works. Just realize it does. You do not get a phone number that they can text. They can only initiate the conversation via the email address you choose when you first run the application.

    SMS doesn't mean that it needs to be sent to a phone. It can be sent to anything so long as there is a necessary gateway in between that converts the information around.
  10. sidewinder macrumors 68020


    Dec 10, 2008
    Northern California
    No. Let's say you are using Textnow Unlimited by Enflick. Enflick has their own servers that the iPhone app communicates with to send and receive messages. Enflick has SMS gateways to various carriers. When you send a message with Textnow Unlimited, the message goes to an Enflick server and is send out via an SMS gateway to the carrier. When your friend responds to your SMS, it goes back to Enflick and is sent to your phone when your open the app. They use Apple's Push notification server to push the notification. If your friend wants to initiate an SMS message, he needs to send it to the SMS email address you get from Enflick.

    I hope that makes it more clear.

  11. yalag thread starter macrumors 65816

    Nov 18, 2007
    Thanks for the explanation. What is the instruction like? Is it to reply with email? Does anyone have a screenshot of what the SMS is like when my friends see it?

    Sorry for the question, just wanted to make sure I know what is going on before making a purchase.
  12. IronLogik macrumors 6502

    Jun 15, 2009
    It looks like a normal SMS. The big pitfall is that you do not receive a phone number that they can send to. The messages get to you via an SMS gateway. It's fairly complicated but it works.

    The SMS will include the name you enter into the application, the email address you choose to use in the application's setup (yourname@service.something), and your message.

    It basically looks like a text message without a phone number attached.

    It works fine. There are a few issues with phones that support threading of messages. Such as the iPhone, the fake number that the recipient responds to changes from time to time and will start new threads making it look like it was sent from someone else.

    It's the cost of having free text messaging. If you want things to work perfectly. Pay for the text messaging plan from your provider. If you want something that works with a few gotchas here and there but costs significantly less buy one of the applications like Textnow, TextFree, or FreeSMS or whatever. Just realize that it isn't perfect. But does as they advertise.
  13. kicko macrumors 65816

    Aug 26, 2008
    I was explaining the ability of the app, not how SMS works. Thats a different question...
  14. IronLogik macrumors 6502

    Jun 15, 2009
    SMS does not allow for sending of messages to email addresses

    MMS does however.

    Forgot to make that point earlier.
  15. bozzykid macrumors 68020

    Aug 11, 2009
    Yes, it is really sending it as a MMS message from the app's servers. And any MMS user can respond to a MMS with the recipient being an email address. And the app's servers catch the incoming email sent via MMS and send it to your iPhone.

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