Do you recommend requesting delivery receipt of SMS for M2M applications?

Yes and no.

It really depends on the application. A delivery of a SMS is 6 -10 seconds, up to hours and maybe never. In case of emergency SMS can be a risk. Worst case the GSM network is busy. A good example are public events like soccer games or outdoor music festivals in urban canyons. Myself is living close to Hannover. The biggest event in telecommunication is called Cebit. It is each year in Hannover. During that time the GSM operators install small GSM base stations  to cover the area. In case of emergency like a bigger accident or fire thousands of people will pick up their phones. The voice channels will be busy, the SMS channels will be busy and GPRS will by busy as well. BTW, the fastest communication channel in GSM is called USSD.

No SMS delivery request, because we would like to save power

Try to track an eagle. It is possible and the hardware concept I am using is the lightest and the concept with lowest power consumption. The concept use no  SMS delivery request. It is wake up, catching a GPS-fix (very fast because I am using A-GPS together with world highest sensitivity), powering on the GSM module, sending one SMS and going back  in deep sleep mode.

No SMS delivery request, because it will kill the server

If you send tons of SMS by several GSM modem wired by RS232 to you server, then SMS delivery request will kill you. You have no control when the SMS delivery note will be send. It is just in time, later or never. Anyhow, transmitting a SMS has lower priority, than receiving. If you try to send a SMS in same time a SMS comes in, the your GSM modem will give you “Error”. If you activated the enhanced mode then the answer is “SIM busy”. The reason is simple. An incoming SMS will be stored on your SIM card. The SIM card is micro controller with I2C-bus. The I2C-bus is blocked by your incoming SMS. The GSM modem will answer with “Error” or “SIM busy” as soon you try to send a SMS. Be aware thata GSM modem  on R232  can send 6 to 10 SMS per minute.

No SMS delivery request, because it is not secure

In case of alarm it makes often sense to send the SMS and after that to start a voice call to the same person (maintenance engineer, nurse, supervisor). As soon the person picks up the phone, you can be sure that the information was delivered. Worst case they get the voice call, before they get the SMS and with big luck the SMS will be delivery minutes later of even never. Picking up the phone by a human is an end to end acknowledge that you can write to your database and later on print in your report.

SMS delivery request, because time and server capacity is no problem

If power consumption is no problem and if capacity is no problem ether, then SMS delivery request is a nice feature, because it is in Germany free of charge. If you get no acknowledge, then what to do? Sending again? If you do that, then build a SMS limiter by software in your application. Why? I just would like to minimise your risk.


  • 24 hours
  • 31 days
  • 60 minutes
  • 60 seconds
  • Each 6 seconds on SMS
  • Euro 0,12 per SMS
  • ends in a bill for Euro 53568 after one month with one M2M device

25 years in radio communication and more than 15 years in GSM and GPS have shown me tons of user mistakes. I have seen the bill of Euro 53648. I have seen other bills, where companies would like to hire me for consulting. They developed a M2M device, that called to a special number in a software loop. Each call was Euro 2,50 .

With the right hardware and software concept people can save a huge amount of money. Anyhow, there are still people on this nice globe that ask for the price for 100.000 GSM modules, without to have a hardware, software, marketing or sales concept. The opposite are people that emailing me or calling me and ask what I have to charge per day consulting. I also like business friends, that just place sample orders without to ask for bulk prices, because they are sure to get the best price.

Thanks god, I am in the position to select the projects. I love people that do not talk to much and place trial orders. Nobody shall reinvent the wheel. I am glad to share my long term M2M experience with my customers. Last but not least everybody can reach me easy by email to harald.naumann (at) or by using the form.

Updated: 2011-07-24 — 6:06 PM

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