This thread, which links to this project, got me interested the idea of wireless gadgetry that communicates via SMS.
The Motorola C168i used in the Open GPS Tracker appears to have gone the way of all cellflesh: obsoleted and discontinued before their batteries have had a chance to self-discharge.
I've found the V176 and C261 at a local close-out store (which might also have a similar serial interface, according to the image posted on this thread). But confirming that is very difficult: "Has a TTL serial interface" is not exactly a common bullet point in consumer phone reviews, and trying to find out through google turns up hundreds of "Buy crappy cellphone accessories cheap!!" and "How to unlock your phone like the l33t hax0rs" sites. Maybe there's some signal buried in all that noise, but I couldn't spot it.
Has anyone come across some answers, instead of the questions about "Does this phone work?" that seem to fill all the discussions I've found so far?
The T193 wasn't on the list of "candidates" on that thread I referenced, so that's not too surprising.
The ones that are listed are: C168, C168i, C257, C261, V175, V176, V177, W220, and W375. It appears that the determining factor is that those phones are built on Moto's G24 cellphone "base module" and have a TTL serial interface wired to their headset jack (the datasheet says the module supports both serial and USB connections, so the module is probably also used in some USB-only phones).
Maybe I'm overlooking something, but does the phone have to have a serial interface jack on the outside? If these phones are built on the G24 base, which I'm assuming is the same across the product line, then they should all have TTL serial IO, whether it's on the outside of the phone or not. The case could be cracked open and I'm sure you could find the lines for TX and RX.
Or are we talking about the feature being enabled on the G24 chipset, hence it would be on a jack anyway?
With the fine pitch SMT packages used in modern cellphones, if the TTL serial IO doesn't go somewhere it is probably inaccessible even if you open up the phone (some ball underneath the middle of a package with no actual access.) Presence of a serial port doesn't necessarily guarantee software to support doing anything "interesting" with the data that arrives on that port.
And the goal is a phone that you don't have to open up just to talk to, and a phone that will do something useful when you talk to it on its serial port.
does the phone have to have a serial interface jack on the outside?
For the moment, yeah: partly because it provides assurance that the serial interface feature is available (e.g., not disabled in firmware so they can use those CPU pins for a camera interface or somesuch), and partly because I don't have the equipment and skills to hack the super-fine-pitch SMT boards you find in cellphones (This is one of those cases where age and treachery does not overcome youth and enthusiasm :().
Even at dollar-store prices, money is too tight to buy a bunch of phones without high confidence that they'll work out. And it's hard to find which phones are even made with that chipset, much less whether they support the serial interface.
I did a little research this afternoon. If you're willing, you can get a c168i for $15 or so. Since it's a GSM phone, it'll work on tmobile, and their prepaid is reasonable @ 5¢/10¢ to receive/send sms. I think you have to add money to the account ever 90 days or so, but other than there aren't any costs. Unlike AT&T, tmobile doesn't push back a message every time you send something from the phone. I have a project where I'm considering something like this myself, and I'm kind of leaning on going with an old phone rather than trying to find a new one. Not the best solution, but one that should work.
Yeah, it's fairly common in the US. Most carriers (as I understand it) provide that you don't have to pay for sms you don't view, but with some phones that's nearly impossible. But yes, we have to pay for sms sent or received...
Kinda ridiculous since SMS uses almost no bandwidth, just uses spare space on the control lines.
Providers in the UK fall over each other to offer cheap "unlimited" deals. I'm on my second contract with Orange, and this time I'm paying £22/month for 400 mins, unlimited texts and (pretend)unlimited internet on a BlackBerry.
US phone companies are infamous for charging extra for things that should be free, or even cheaper than the default. This started with touch-tone dialing back in the 70s. It's all "creative pricing", designed to get the most possible dollars out customers, given infrastructure costs that are essentially constant. I hate it. The people who actually USE their phones enough to justify flat-rate plans are less unhappy, I think.
OTOH, I pay about $20 for (up to) three months of service on my daughter's pay-as-you-go cheap phone. That includes 60 "minutes" of air time (this is supposed to be an emergency-use phone), and incoming/outgoing text messages apparently count as 0.3 minutes. That's pretty reasonable. (The phone itself was "free".)
This started with touch-tone dialing back in the 70s.
Remember that, in those days, every phone charge was set by the various government regulatory agencies.
The touch-tone tariff was just a continuation of the "soak the rich" philosophy exemplified by high rates for business phones, modem lines, long distance, and other services to subsidize the cost of unmetered local POTS for the masses. Tone dialing was seen as a "luxury" feature that could be taxed to spare poor and lower-middle-class folks the capital costs of upgrading aging central office equipment.
As an example, I have 2 old SonyEricsson mobiles, that I can talk to over the serial interface.
My old SE t68i works fine, but only supports SMS in PDU mode, which makes it not so interesting to use.
On the other hand, my old SE z600 suppors SMS in text mode, making it very easy to use.
So far I have only tested sending SMS'es from the arduino --> phone, not tried to recieve anything.
Oh, and just to show off;
I have a free mobile plan. Costs nothing, and includes 50 SMS'es and 50 minutes per month, and costs nothing!
Because it's documented that some of them work, and the serial interface is accessible through a connector that doesn't have to be bought in 500-piece lots from a single source in Japan (Yes, as a matter of fact, I am still bitter about Sharp screwing Zaurus early adopters by using a connector that only medium-to-large businesses could get during its first year on the market >:().
If you know of a phone (especially one in current production) that has a documented serial interface through a connector that doesn't cost more than the (carrier subsidized) price of the phone, please do suggest it.
If you know of a phone (especially one in current production) that has a documented serial interface through a connector that doesn't cost more than the (carrier subsidized) price of the phone, please do suggest it.
The required feature is that you be able to initiate and deliver text messages from/to this serial port, rather than use it as a dialup modem, right? Just because a phone has an accessible serial port doesn't mean it will have this feature...
I also tried to find such a list with phone models with serial port where I could easily send/receive SMS. I would prefer some old Ericsson from eBay. I found some hints that e.g. a T68i should work, but no list.
