h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

A few quesions on mobile phone text messaging...

1: It was apparently first used as a tool by engineers when they were setting up mobile networks. Why did they use text messaging in particular? Since text messages use the same phone lines, why not just call each other?

2: Why was this feature left in when mobiles became generally available?

3: Why are text messages restricted in length?

4: Why are they restricted to 160 characters, instead of a sensible number like 150 or 256?

I'll have to guess at #s 1 and 2:
#1 : the receiver of the message can read it "later". a voice call would (a) leave no readable trace and (b) requires synchronous action of the receiver to transfer it

#2 : well, looking at the market it's quite a good (marketing) decision to leave this feature in?

#3 : the message block is sent from phone to phone through the telephone service provider's networks via communication protocols (in this case the MAP protocol over SS7 but you may forget all that). The payload of a single transaction in that protocol is 140 bytes, or 140*8= 1120 bits. This block of 1120 bits can hold 160*7 bits. Western script can be presented in 7 bits ASCII codes so you end up with 160 western script characters (Yes, Arab, Cyrillic or Chinese sms messages will have a different max message size).

#4 : (see #3) the programmers of mobile phones and network equipment were probably lazy and wanted to limit a text message to one single MAP transaction (cheaper as well by the way).

In reply to No. 4 only I have a cheap rubbish Nokia 1100 and have 459 character text message facility. Not that I use it much - don't really do text messaging.

turvy

Traveller in Time not messaging text via a phone
"Any number of characters above 160 will be made up of several Short Message Service messages, this is called Multi Message Service and you will be charged for the lot as if they were several shorts.
459 is about 3 times 160, the other bytes are used to 'link' the packets together. "

a 459 character SMS would take three message blocks (and probably would cost three times as much as a "standard" 160 character SMS).
The "long" SMS contains less than 3*160 characters because part of the payload is used to mark (a) that the total message contains three blocks and (b) the sequence number of each block.
mind you, some telephone service providers may not support long messages

Another reason I don't text...


turvy

One assumes "long SMS" is an oxymoron.

B

? u mn xymrn

trvy

Traveller in Time trying not to use abbreviations
"LCD display
TL tube
TLA abbreviation
"

<>

As an engineer you're looking for the quickest and easiest test. Sending a few characters and getting some back meets that requirement without putting unnecessary stress on the network. The less bandwidth the peons are occupying, the more there is for the paying customers.

<>

It was probably continued to support engineering just as before. But then someone in marketing figured out they could sell this as an additional service. Text messaging is a bonanza for wireless companies because it gives them an additional revenue stream while simultaneously reducing network load... it takes far fewer packets across a digital network to carry ASCII text than it takes for voice. With a lower network load, they can support a greater number of customers with the same infrastructure, meaning even more revenue.

It's all about the money.

Traveller in Time not responding to spam messages
"They certainly found a niche, getting informed of the time will cost you for 24 messages a day.

Somewhere someone made the mistake to get the receiver turning up for the cost, opening a great opportunity for easy made big money "

It's certainly true that they included SMS as a service, thinking that nobody would be crazy enough to use it. In the States that seems to be the case. My brother-in-law lives over there and nobody has ever heard of texting. He has to borrow their phones off them to show them how to look at all the texts that he has sent them.

Here in Europe, it caught on, and nowhere (as far as I know) as much so as in Ireland, where we each send more than 1,000 texts a year.

Then again, a lot more people have pagers in the USA than in Britain or Ireland. That would cut down on texting a lot.

I dunno how much texting is actually being used here in the US, but I can tell you that there's a huge marketing push for it, particularly aimed at teenagers in an attempt to teach them that texting is "cool."

In the adult world, SMS can replace paging, which means you don't have to carry multiple devices. Then again, if you really need that level of communicability, you can just ditch the SMS and go straight to the Blackberry.

From what I've heard from american's I have known, phoning is *much* cheaper on mobiles in the states.

I text all the time here in the UK as it saves me a fortune in calls.


Mind you my definintion of all the time is around 120 texts a month - not sure how that matches up to the average 15 year old...

At weekends, I pay 1 cent a minute for calls, and 1 cent for texts. I often find it easier to text.

A few moments call to another mobile here in the UK (depending on your package or contract) is likely to cost a lot more than that.

It's a lot more than that here (depending on your contract of course) - but then, we are rip off Britain still.

Sorry for repeating myself, thought'd I'd deleted at least half that message.

I prefer texting. The receiver is free to reply when they're free, and you have time to compose your message without worrying about noise or voice tone or anything. Its cuts communication down to something more manageable.

>>"Mind you my definintion of all the time is around 120 texts a month - not sure how that matches up to the average 15 year old..."

400-600 a month would be considered an average amount.

My oldest stored text message on my phone is from October 1999. This was when they just changed the different systems to make them compatible. Before that you could only get texts from people on the same network. Has anyone got an older one stored?