Are there any cell phone providers that have plans that are appropriate for low bandwidth data transfer? I’d like to use a cellular modem to log data from a sensor package. I only want to log a few KB a day.
All of the cell plans that I can find are >$30/month and have lots of features like voice and SMS that I don’t need.
Has anyone had any success using a pre-paid plan and transferring data over SMS?
Bell has these prepaid data plans that are suppose to be for iPads and other tablet devices but my brother was able to get the plan on a sim card for his iPhone when we came back to Toronto over the holidays.
You can just ask any Bell representative at a kiosk to give you one of these plans for your phone instead, but you have to go in person because they are not actually suppose to give you these plans on a phone sim card.
Also these are no contracts attached, you pay and for however many data you use starting with 20 bucks.
In the biz, this is called Machine-To-Machine, or M2M. In Canada, both Rogers and Bell offer this service, but because it’s aimed at big companies it may be hard to get service from them. Rogers now seems to offer a dev kit for $200 that gets you 3 SIMs and 50 SMS messages per month, plus 30 MB of data for the first 6 months.
We built something similar to that for a prototype at RIM back in the day. We wrote a general purpose transport system on top of the BlackBerry’s PIN messaging system, and used it for all kinds of P2P data exchange. I think PIN messages were limited to 512 bytes (including the header), since it was based on the old Mobitex system.
To transmit some data, we would first construct an application-level packet (the details aren’t important), and hand that off to the transport. The transport began by performing a handshake with the intended recipients to agree on a connection number. With that, the next step was to encrypt and MAC the packet for each of the recipients. (Oh, did I mention we built in RSA encryption?). Then the transport would break down the packet into chunks of about 450 bytes (to stay below the maximum PIN message size) and insert a header made up of a distinct tag, connection number, and sequence number, before sending out the message by the default PIN sending system.
Any time a PIN message was received, a program on the phone would check the beginning of the message for the distinct tag associated with the application. If it found the tag, it would read the contents of the message, then delete the message from the phone’s inbox to prevent the end-user from getting a message notification and stop it from appearing in the inbox.
With the contents of the message, the device would wait until all the messages in the sequence for that connection had arrived (PIN messages may be delivered out-of-order), reassemble the encrypted packet, then verify and decrypt the message. From there, the packet was handed off from the transport for regular processing.
You could easily do the same thing with SMS. With SMS you have 140 bytes, which is 160 characters from a 7 bit alphabet, minus the characters that get eaten up by your tag, connection number, and sequence number.
We’ve been using DataJack for months with very good success. We chose them for a variety of reasons, although our first attempt about 2 years ago was a bit disappointing. Since then, they’ve introduced a MiFi device and we’ve been very pleased with the service for our low bandwidth M2M (IoT) platform. We usually use less than 100MB/month and so our costs are <$10/month for each site. It’s the best deal we’ve found to date. We had gotten pretty heavily into TruConnect, but their support is terrible. We have several of their MiFi devices if you’re interested in purchasing them at a big discount!