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SMS Messaging Unreliable
Lovejoy writes "From a Reuters story: Keynote announced today that in its two-week, 26,000 message test-period 7.5% of its text messages never reached their destinations Ouch. I don't have SMS - Is this report consistent with your experience?"
Works here (in Finland) well enough. I'd say 99% of my messages reach their destination.
SMS messages can be set to "expire" if the are not delivered in a certain amount of time. All the phones I've owned had this set to "now or never", so if the message couldn't be delivered at the moment it got trashed. Mos users, of course, have no idea this setting exists.
AT&T got me started on SMS with a "free for now ..." package, then switched to one where incoming is free, and outgoing costs 10 cents each. So I adapted and basically never send a text message from my phone. However, it is handy that you can e-mail messages to an AT&T cell phone at 5055551234@mobile.att.net (i.e. insert appropriate phone number) for no cost. So I regularly e-mail my wife's cell phone from my desktop.
Crispin
----
Crispin Cowan, Ph.D.
Chief Scientist, WireX Communications, Inc.
Immunix: Security Hardened Linux Distribution
Available for purchase
How is $0.10 a message (with Cingular) a free service? My carrier charges for both sent and received messages, although it's possible to buy your messages in bulk for a discount, i.e. 100 messages a month for $3.99, 200 for $5.99, etc.
"It's Dot Com!"
The handset gets a received receipt via the network when a) the message is waiting to be received by the other handset and b) the message is delivered successfully. If your handset doesn't get the first receipt back immediately, the network received receipt, it gives you an error. You can frob a bit on most Nokias to show you all this, it's really handy.
Feel that power? That's mah MOUSING FINGER
Actualy I do have unlimited SMS, but that's because I develop SMS stuff for the Telecom Operator.
...)
Here nobody pays for receiving SMS, except if they were sent by a service requested by the client (eg: Stock quote, wheater,
I've also never received SMS Spam, because sending SMS is very expensive and it doesn't pay to send SMS Spam! (At least here in Europe).
Anyway, if I do receive a SPAM SMS, I'm certanly not gonna pay for it!!!
Is this report consistent with your experience?
:)
Well for what it's worth,
1. International (roaming) messaging is a disaster. You're lucky if anything arrives, and if it does, it can easily be delayed a few days. Once it gets through, you're likely to get the message several times - people reported up to seven times. Can you say ACK ?
2. During peak loads, it looks like the (Belgian) operators give priority to packets originating from subscribers -- ie people who are not using a GSM-version of a calling card containing n minutes / m messages. This was especially obvious at new years' eve -- everyone I know with a subscription got through with every single SMS; people with a card got exactly zero messages through the stampede. If delivery fails, you get a notice though, and afaik you're not billed.
I'm in the UK and I can't say I've EVER known an SMS to disappear. However, around 10% do seem to suffer from delays of up to an hour or more. Most are virtually instataneous. This sounds like someone's got an anti GSM agenda to me...
That was classic intercourse!
I haven't had a message that actually failed for more than two years now I guess.
In my country (Greece), SMS messages never get lost. Even in peak hours you get your message right away in a subsecond.
Actually, mobile users in Greece use SMS messages more often to communicate that actually making a call. The phone companies also know this and make much more money from SMS that calls. The also have special offers for sending SMS messages cheaply while the call costs are very expensive (and it is very popular).
In this new year's eve (the time when the network has the highest traffic) 50 million SMS messages were sent in 15 minutes (for the population of Greece that is about 5 SMS messages per citizen)!
I'm from Belgium and for as far as I can remember, I've never lost an SMS.
I have my cellphone set that for every SMS I send out, I'll get a report on it's status. 'Pending' if it hasn't arrived, 'Recieved' if it has.
90% of the time, they arrive instantly. Delay's are usually attributed to the recieving end because his/her cellphone has been switched off, battery died or their SMS box is full.
Except for things that need urgent attention, I find SMS to be very reliable. More reliable then email if you ask me. Email has the tendancy to subject itself to Murphy's Law everytime anything important has to be sent out or is expected.
With the mass popularity of SMS in Europe most carriers have had to invest in keeping up with the demand in sending messages. I wouldn't be surprised if they made more money with SMS then through regular phone calls. People rarely make any phone calls anymore.
And since there is a cost with every SMS sent, it still remains spam free.
Pretty much all of the messages I send get through, actually I can't think of a time when one hasn't. On most phones, theres an option to request a delivery report, where you get a message back saying when the other user has recevied the message. It works pretty well, to the point that if the person has their phone switched off, you only get the message when they switch their phone on and actually receive the message. Not sure if its available on all networks, but it works fine on vodafone UK, even when sending cross-network.
I like to get alerts on my cell phone for weather and news, so I signed up for the services on Yahoo. At first I didn't want to reveal my phone number, so I used a forwarding email service. All I ever got was the occasional (about once a month) weather messege from yahoo and a newsletter from the forwarding service.
With the miserable rate, I added my original number/email address to the service and subscribed to all the same alerts. I was getting all my weather every morning for the first week or two, but now I only get weather once a week and I never get news updates.
There is a reason I always have to ask my friends if they got my SMS
Urgo: "I want to live. I want to experience the universe and I want to eat pie!"
Jack: "Who doesn't??"
Here in Australia mobile service is something like 40c/minute, 1 minute minimum, and SMS's are 20c apeice. That's the main reason. And once you get used to it you realise that it's a lot more convenient for certain types of messages. And you can bulk send them to heaps of people at once. There are lots of reasons.
I have a t68 world and a t28 world. the t68 is for my cingular wireless here in the states. Every third sms croaks with this service, while my Slovenia phone co, Mobitel, can get every sms to me when I cut on my t28 in the States, or anywhere for that matter. I think it really has to do with the provider and the importance that they put on sms. Cingular charges 3 bucks for 100 sms's a month, while Mobitel charges nothing and only 1 tolar a minute for phone calls within SLO and 55 tolars a minute for international roaming for my Cingular phone. Cingular charges 400 tolars a minute (2 bucks, roughly) for a minute to my Mobitel phone. US GSM and mobile phone plans in general are a ripoff. How can Slovenia, while pretty prosperous for a former Yugoslav republic, keep rates so cheap? It can just be 90 percent market penetration alone!
Comparing it to Windows will be a moot point, since El Dorado is going to have a 40% larger code base than XP.
SMS is never intended to be reliable. There are many places that the SMS can be lost. So, lets go through a description. :) Before we begin, let me prefix this by saying it's all GSM, and probably wrong (going from memory), but probably close enough.
Acronyms:
Your handset is connected to a base station. The base station talks to the SMSC and gives the SMS to it to deliver. The SMSC then attempts to forward it on to the destination SMSC, who will send it to the destination BS and finally to the destination phone.
Now, add in the fact that a destination phone may not always be available to receive the SMS. It may be outside of signal range, have a dead battery, or simply be turned off. So the destination SMSC has to store the SMS. The SMS is usually lost because the SMSC has to flush it, like a congested router.
The next place that it can be lost is in the originating SMSC. Consider, it takes a _lot_ of negotiation between carriers to get links set up, and add more. Cost/SMS, payments, etc have to be agreed. Now, imagine you've saturated that link and need to send another message. Yep, it queues up on the sending SMSC too, only he doesn't care as much because you're not his customer. :)
Let's look at some math:
- SMS/subscriber/day: 10 (billed+others)
- Number of subs/SMSC: 2m
- Size of SMS: 256bytes
- Percentage lost: 3%
- Number of lost messages: 600k
- Space needed to store all lost messages until delivery: 600,000 *
.25kbytes = 150megs
So, assuming that all messages can be delivered in 24 hours, you would have to find 150megs of free space on the system to get it to work (good luck). Of course, the messages would be late and confusing, but who cares!An SMS is an unreliable, time limited message. It doesn't carry long term value, and is usually used for "ping" type messages. Top it off with TV shows receiving votes by SMS which result in rates going from 100SMS/second to 500SMS/second, and you get an idea into how hard the problem can be.
Jason Pollock
7.5% seems highly unreliable and not in keeping with TCAP, which is the protocol ontop of which SMS is build. SMS or MAP, Which is "Messaging Application Part", built ontop of "Transaction Capability Application Part" are high level SS7 protocols which are meant to be reliable. One of the probable reasons it might not be would be the Messaging Center, SMSC! These are notably shite, with both Logica and CMG, which is now Logica, basically selling very expensive shite. However the exponential backoff algorithm on delivery is fairly long, and it could be the case that an SMS is received a long time after it was sent, though what has often happened is that an SMSC gets overloaded, and the admins reboot it... and pop go all the messages. I do believe that the posting refers to the states, because in Europe it's just dandy. That would be down to operators experience with SMSC's, Gateway MSCs "ie connections between differing cellulare networks", links, number portability etc... SS7 is fairly baroque!
Cheers!
Kahunga the Behemoth.
I'm seeing a lot of "Why the hell would someone use a cell phone to message when they can just talk?!?"
Well, besides the giggle factor that comes into play the first time you message a friend who's staring at you from right across the room, my answer would be because IT QUIET!!!
In the movie theater and your mom/boss/significant other wants to know where you are, or why the hell you aren't someplace you're supposed to be? Your phone on vibrate can show you who's calling you, and you can quickly type in a message and reply back with information without disturbing those around you.
On New Years Eve, I was at a Rave at the LA Sports Arena. Do you think I'll really be able to hear or talk to anybody next to a wall of subs blowing out my ear drums? Considering there were quite a few people there, I also get separated from my friends. Where's my buddies? When do I know when it's time to go? How far is Kenny getting with that Bree chick (seriously!)? There would be no way we could talk on our phones, but we were still able to communicate with our SMS text messages.
Now granted, SMS isn't nessecary, but then again, this is Slashdot. How often do we do things that are truely nessecary?
-Kefabi
This is definitely NOT what I'm seeing. Not here in Finland, but also not when I've been travelling in other countries that use GSM. I consider it about on par on reliability with email.
First of all, you get a notification immediately on the phone if the message was delivered or not, just like when you send email. In addition to that, there's a return receipt type system that many people use. I personally don't use it because I've never had any problem with messages not getting through, but I know people who do use it and I've never heard them complain about messages getting lost.
I'm wondering if the SMS messages talked about in the article are really GSM SMS messages? It seems that all European users here are saying that they have no problems what so ever. And this study was made in the USA. Considering that GSM is hardly used at all in the USA, I'm kinda wondering if they are just using "SMS" to describe whatever proprietary text messaging systems are in use in the USA. The true SMS is that of the GSM system, where you can send an SMS to any other GSM user in the world, regardless of their or your telco, with litterally billions of messages sent every day (more than email, as a matter of fact).
In europe the phone tells you the moment you send your message if the network has accepted it or not.
If the network has accepted your message for delivery, it will try to deliver it for a certain amount of time (this is configurable on the sender's phone), I have set mine to 72 hours.
You get a delivery report the moment the network has accepted your message, and another one the moment the intended recipient has gotten it.
If after the delay the message couldn't be delivered (read: recipient cellphone was offline during all this time) you get a delivery report for failure, so at least you know it's failed.
This works in almost ALL european countries, the few exceptions are certain operators (like Bouyges Telecom) which filter SMS coming from foreign numbers.
I'd say the service is great, reliable, informative and cheap. As a result, SMS has mostly replaced pagers in Europe.
Is this report consistent with your experience?
Back in 1998 I was working on a frost alarm system for farmers (in Italy). Subscribed farmers would get an SMS containing information about the temperature/wind/precipitaion and a number of other parameters, from hundreds of weather stations all over the area, whenever a configurable event was triggered.
During our test phase all messages arrived, but unfortunately the provider could not handle the rather consistent load, and therefore a high percentage of the alarm SMS arrived only hours (or even days) later, which was - for obvious reasons - useless in that case.
Since then providers in Italy have expanded their message centers, and although I am not working on any such project currently, some colleagues of mine are, and they confirm that nearly all messages arrive at destination, and the ones that don't usually have invalid recipient mobile numbers. You get confirmation messages that not only let you know a message has arrived (or not), but in case of a successful delivery you can also know the exact time the recipient received your message.
On another note, maybe slightly offtopic: some posters have expressed their fear of Telemarketers and Spammers taking advantage of SMS. Personally I have only been spammed by one single company: my mobile provider. That's the main reason why I have changed provider lately (after 5 years). I have never gotten a single spam SMS by anybody else.
In Italy (don't know about other countries) you can get SMS over landlines, too, if you have an SMS enabled phone. If you do not have such a phone, the message will be read to you by the system. Now this is something a bit more scary: it is much easier for Telemarketers to collect a huge database of landline numbers than mobile ones, although since Italy has issued the "privacy law" a few years back, unsolicited advertising (via snail mail or phone) has dropped from "a couple a day" to "max 2 a year".
The most definitive book on GSM is unfortunately hard to get:
5 9
http://www.amazon.com/exec/obidos/ASIN/09455921
The GSM System for Mobile Communications
Mouly, Pautet
From the people who worked on the standard.
Also, note that in countries with a properly working GSM network (that is, almost anywhere except the US), SMS do work just fine despite the fact that they have no reliability guarantee and no maximum delivery time guarantee BY DESIGN.
Also, most people are using SMS delivery notifications to get information if and when their SMS has been delivered. That is, you get notified by SMS if your SMS has been delivered, with a timestamp, or are notified when your SMS has been delayed or lost, also with a timestamp. Using this backchannel and a simple timeout, reliable SMS delivery and notification can be implemented just as TCP is being implemented on a protocol like IP that just guarantees "best effort" delivery of packets.
Finally, why is SMS popular? Because it is quiet and it is asynchronous. You do not have to answer the phone in order to receive an SMS, but can handle the issue when you are ready and have the time. In Europe, you do send an SMS for just about everything, unless the matter is urgent and requires immediate attention of the callee.
Kristian
LogicaCMG as of this year!
If you're into SMS, you might do well to remember that company: I believe that Logica and CMG (now LogicaCMG) together have 85-90% of the world market for SMS software.
So if you lose a message, you know who to call.
If construction was anything like programming, an incorrectly fitted lock would bring down the entire building...