Naked Science Forum
General Science => General Science => Topic started by: neilep on 12/11/2012 20:51:05
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The SMS (Short Message Service) was introduced in GSM handsets.
It utilises the fact that telephone networks send messages to each other to set up voice calls. By inserting a user-generated text string in such a message, a simple data service could be set up over what was originally a voice-only application (mobile telephone). Because it is competing with a voice call, mobile operators soon discovered that they could charge the same as a telephone call for something that imposed less load on their network than setting up a telephone call. http://en.wikipedia.org/wiki/SMS
The GSM version of SMS delivers up to 140 bytes. Operators in Australia charge up to 25c for each SMS (although they often include "free" text messages in a contract). This works out to a massive $1785 per Megabyte. This is 10,000 times more than the same operators charge to download a megabyte on a fixed line in Australia (although they often include "free" Gigabytes in a contract).
Over time, mobile phones introduced some data services, and mobile networks were gradually optimised for more data transfer (the most recent mobile standard LTE, is totally IP-based). However, the introduction of the iPhone (and subsequent easy-to-use phones) caused a huge increase in the amount of data that users downloaded, causing overload of mobile networks around the world. Because these services were competing with fixed-line broadband services, the price per Megabyte was much closer to broadband pricing.
These downloads used the IP protocol that is used by the internet, and is based around messages which can typically carry 500-1400 bytes of data (http://en.wikipedia.org/wiki/Internet_Protocol). People using these services could send a very long message, at the much reduced prices of IP services. However, because these texting protocols aren't included in an international standard like GSM, there are more interworking problems between different messaging services on different device brands.
Thus we have the traditional SMS, with very short messages at a high price, and the newer IP-based messages services with much longer messages at a much lower price.
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Thank ewe very much evan_au ! for your very helpful explanation.
sorted !!
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A normal (strictly SMS) text message is a feature of the GSM mobile phone and operators' infrastructure. The mobile phone company themselves explicitly route the message to another handset (by phone number), and they bear the cost of this (although it must be miniscule).
An instant-messenger (such as WhatsApp, or Skype IM) sends messages using an internet-based protocol using the more-general 'data' capabilities of your phone. As far as the mobile networks are concerned the message is "just" miscellaneous internet data which, like all your mobile web-browsing, they just route onto the internet at their end, then forget about. Even if you think you're sending to a mobile number (like with WhatsApp) really you're just sending to an internet-based account *associated* with that number. (In fact with WhatsApp it'll associate the handset with the number of the SIM present when you register for WhatsApp - and even if you swap SIM cards later it'll still send and receive messages for the number of the original SIM).
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Fantastic !!..Thank you so much techmind !! yayyy !!
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It's also my understanding that if a phone is switched off or out of range when an SMS text is sent to it, the network-operator of the recipient's phone will temporarily store the message and attempt to retry delivery.
By contrast, for other "instant-messaging" systems the (internet-hosted) company running the messaging service will store messages when the recipients phone is unaccessible. Depending on the service architecture, the phone may 'poll' the messaging service periodically for messages, or it may be able to receive messages (or notification of pending messages) by a push-mechanism.
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This is not an answer, just an observation. Personally, I almost never use SMS any more, since I can get into all three of my e-mail accounts on my phone. I almost always e-mail. 10p a time to text, a days internet connection for a flat rate, currently 0„51 for 100 MB and I can send as many messages as I like. Never used instant messaging. Currently, I have 1 GB of free data from Virgin Mobile and 30 days to use it, as a sweetener 'cause they just raised their prices to what I stated earlier. Which is how I'm writing this on my phone right now. 1 GB for free! Yay!
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OK, that was supposed to say £1 for up to 100mb in a day. For some reason, the pound sign on my phone came out as a load of gobbledegook. I wrote this correction on computer. What's the correct spelling of gobbledegook, anyway?
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Basically SMS text messages are taxed/charged by the network provider to help them pay for their network. Originally they were free, but they realised that that meant that the user wasn't using their phone, so they charged for them as well, because they could; and they made amazing profits, particularly since it doesn't actually cost anything much to provide.
The instant messaging stuff is much harder for the network providers to charge for because it's an internet service; they could and IRC previously did tend to block it to force people to text, but it upsets their customers and tends to draw attention from regulators; so they're more about charging by the gigabyte these days rather than per text/phone call so much.