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This is kind of a weird article, it almost contradicts itself a bit. As the article mentions, SMS'es are kind of piggy-backed with control signals sent on the

This is kind of a weird article, it almost contradicts itself a bit. As the article mentions, SMS'es are kind of piggy-backed with control signals sent on the network. At first they found they could tack on a 128 character message, but then reduced the character set further to get to 160 characters. What isn't clear in the article is when this 'proof' that 160 was enough occurred. Did it occur after they figured out they could jam 160 in, in order to validate that 160 would be useful enough? Or did it really occur in the order that the article talks about, that they first picked 160 characters out of the sky, then managed to jam that into the signal. I find the latter to much less likely. 160 just happens to be the most you can fit in to the packet, which he then validated was probably enough to be useful. Anybody know definitely otherwise?

pwg 16y ago
Here is part of what the Wikipedia article has to say, which appears to show that the size limits were indeed the result of the existing design, and so the only 'proof' here was that the existing amount of data would be sufficient for the intended purpose. Which makes the linked article another example of the mainstream press getting themselves all confused when it comes to cause and effect in technology. A key sentence in the Wikipedia article was that SMS, so limited, could be implemented with software changes only, making its rollout by far easier and more likely to occur. http://en.wikipedia.org/wiki/SMS http://en.wikipedia.org/wiki/SMS: "The innovation in SMS is Short. The GSM is optimized for telephony, since this was identified as its main application. The key idea for SMS was to use this telephony-optimized system, and to transport messages on the signaling paths needed to control the telephony traffic during time periods when no signaling traffic existed. In this way, unused resources in the system could be used to transport messages at minimal cost. However, it was necessary to limit the length of the messages to 128 bytes (later improved to 140 bytes, or 160 seven-bit characters) so that the messages could fit into the existing signaling formats. This concept allowed SMS to be implemented in every mobile station by updating its software. This concept was instrumental for the implementation of SMS in every mobile station ever produced and in every network from early days. Hence, a large base of SMS capable terminals and networks existed when the users began to utilize the SMS."
dkersten 16y ago
Having spent two and a half years of my life getting intimate with GSM-based (ie, not CDMA, though a lot of the protocol stack is the same) SMS messages (I worked for a company that did security, anti spam, anti fraud and other VAS systems (parental control, blacklist, SMS backup etc) for mobile operators)[1], I know a little bit about it. Admitedly I could tell you a lot more about the protocols used by SMS than its history GSM networks consist of two signalling links: voice and control. The contol is used to, for example, set up or terminate voice calls. This meant that, in practice, the control signalling links were generally idle and so they piggy-backed SMS on it. I don't know anything about the 128 bytes, but the 160 characters comes from the 140 byte payload, when using the 7bit GSM default packed alphabet. I don't know the numbers offhand (been a year since I've worked there now), but quite possibly this is, indeed, the maximum packet size available, though there certainly is a large range of differently sized packets. In fact, a lot of things are piggy backed on the SMS payload. For example, when using concatenated messages (or binary data - there was a range of predefined things that are biggy-backed on SMS as "user data"), the header telling the phone which message it is is placed at the start of the message payload (reducing the maximum characters per text by (I don't remember offhand anymore) ~6 octets. Of course, 160 characters only applies to the 7bit GSM default alphabet. SMS messages also support 8bit and 16bit payloads. Mobile operators absolutely love SMS as it is probably the most expensive form of communication they offer. Somebody else below mentioned ubiquitous internet as an SMS replacement. While I think its true for a lot of people in well built-up parts of the world (and who have a smart phone, a lot of people still don't), its certainly not global. Hell, even here in Ireland theres areas where cell phone reception is pretty bad, so while you might manage to send or receive text messages, if you want to go online you're out of luck. Other, poorer, parts of the world are even worse off. Actually, I remember one company at the 2009 GSMA Mobile World Congress in Barcelona was demonstrating a solar panel powered mobile cell tower, for use in places like Africa, which was designed to provide better coverage of mainly SMS to large open spaces. [1] http://dublindan.posterous.com/things-ive-worked-on-4 http://dublindan.posterous.com/things-ive-worked-on-4 We did a lot using transparent Home Routing http://en.wikipedia.org/wiki/SMS_home_routing http://en.wikipedia.org/wiki/SMS_home_routing The wikipedia article says that transparent home oruting is limited. I disagree. At least in the lab, we implemented everything from the technical realization (and then some) on a transparent home routing system. I believe when I left the company, others were working on a non-transparent version too (because it is easier/cheaper to get and install hardware for non-transparent operation than for transparent). But then, we did a lot of non-standard things, we just did them in ways that don't interfere with the rest of the network. EDIT: comment didn't end up as interesting as it sounded in my head. Hopefully somebody found it useful nontheless.
wisty 16y ago
I thought that SMS was initially just a hidden feature that engineers could use to test the phones - validating that control signals were coming through. Some teenagers found it, and discovered that it wasn't billed, and started using it. Then the telcos caught on, and realized that a new product was born.

pwg 16y ago

Here is part of what the Wikipedia article has to say, which appears to show that the size limits were indeed the result of the existing design, and so the only 'proof' here was that the existing amount of data would be sufficient for the intended purpose. Which makes the linked article another example of the mainstream press getting themselves all confused when it comes to cause and effect in technology. A key sentence in the Wikipedia article was that SMS, so limited, could be implemented with software changes only, making its rollout by far easier and more likely to occur. http://en.wikipedia.org/wiki/SMS http://en.wikipedia.org/wiki/SMS: "The innovation in SMS is Short. The GSM is optimized for telephony, since this was identified as its main application. The key idea for SMS was to use this telephony-optimized system, and to transport messages on the signaling paths needed to control the telephony traffic during time periods when no signaling traffic existed. In this way, unused resources in the system could be used to transport messages at minimal cost. However, it was necessary to limit the length of the messages to 128 bytes (later improved to 140 bytes, or 160 seven-bit characters) so that the messages could fit into the existing signaling formats. This concept allowed SMS to be implemented in every mobile station by updating its software. This concept was instrumental for the implementation of SMS in every mobile station ever produced and in every network from early days. Hence, a large base of SMS capable terminals and networks existed when the users began to utilize the SMS."

dkersten 16y ago

Having spent two and a half years of my life getting intimate with GSM-based (ie, not CDMA, though a lot of the protocol stack is the same) SMS messages (I worked for a company that did security, anti spam, anti fraud and other VAS systems (parental control, blacklist, SMS backup etc) for mobile operators)[1], I know a little bit about it. Admitedly I could tell you a lot more about the protocols used by SMS than its history GSM networks consist of two signalling links: voice and control. The contol is used to, for example, set up or terminate voice calls. This meant that, in practice, the control signalling links were generally idle and so they piggy-backed SMS on it. I don't know anything about the 128 bytes, but the 160 characters comes from the 140 byte payload, when using the 7bit GSM default packed alphabet. I don't know the numbers offhand (been a year since I've worked there now), but quite possibly this is, indeed, the maximum packet size available, though there certainly is a large range of differently sized packets. In fact, a lot of things are piggy backed on the SMS payload. For example, when using concatenated messages (or binary data - there was a range of predefined things that are biggy-backed on SMS as "user data"), the header telling the phone which message it is is placed at the start of the message payload (reducing the maximum characters per text by (I don't remember offhand anymore) ~6 octets. Of course, 160 characters only applies to the 7bit GSM default alphabet. SMS messages also support 8bit and 16bit payloads. Mobile operators absolutely love SMS as it is probably the most expensive form of communication they offer. Somebody else below mentioned ubiquitous internet as an SMS replacement. While I think its true for a lot of people in well built-up parts of the world (and who have a smart phone, a lot of people still don't), its certainly not global. Hell, even here in Ireland theres areas where cell phone reception is pretty bad, so while you might manage to send or receive text messages, if you want to go online you're out of luck. Other, poorer, parts of the world are even worse off. Actually, I remember one company at the 2009 GSMA Mobile World Congress in Barcelona was demonstrating a solar panel powered mobile cell tower, for use in places like Africa, which was designed to provide better coverage of mainly SMS to large open spaces. [1] http://dublindan.posterous.com/things-ive-worked-on-4 http://dublindan.posterous.com/things-ive-worked-on-4 We did a lot using transparent Home Routing http://en.wikipedia.org/wiki/SMS_home_routing http://en.wikipedia.org/wiki/SMS_home_routing The wikipedia article says that transparent home oruting is limited. I disagree. At least in the lab, we implemented everything from the technical realization (and then some) on a transparent home routing system. I believe when I left the company, others were working on a non-transparent version too (because it is easier/cheaper to get and install hardware for non-transparent operation than for transparent). But then, we did a lot of non-standard things, we just did them in ways that don't interfere with the rest of the network. EDIT: comment didn't end up as interesting as it sounded in my head. Hopefully somebody found it useful nontheless.

wisty 16y ago

I thought that SMS was initially just a hidden feature that engineers could use to test the phones - validating that control signals were coming through. Some teenagers found it, and discovered that it wasn't billed, and started using it. Then the telcos caught on, and realized that a new product was born.