Comms, it is true that most phones do not have a true GPS that can receive and decode satellite signals. I know Nokia and Sony Ericcson have it on selected models, but absolutely not on the cheaper models. I don't know squat about Iphones, so I'll take Martin's word on that system.


I think the source of confusion is that some service providers call their cell tower based location services "GPS", using those 3 letters as a generic name for location services. I've seen that service as an option on $20 pre-paid phones from walmart.... (Of course you would pay dearly for that location service... it's just another way of fooling teenagers to part with their parents money: Look, the phone is just $19.99... and it has "GPS", Mommy please?).

A phone that advertises "GPS" has a GPS chipset in it. It's really that simple.

I suggest: http://electronics.howstuffworks.com/gps-phone.htm
for information.

There are a LOT of phones with GPS chipsets: Link to GPS Phones List

In terms of focus for GPS in phone devices, it's definitely for vehicle, on-road navigation.

In you really want to go deeper into this, I suggest you read iPhone vs. A Stick.

And then there are those of us with Blackberrys from Verizon. This company decided to deactivate the GPS chipset in my BBery 8830 so that I cannot use third party navigation software. I need to pay $10 a month for their navigation service.

I own a Garmin Nuvi, so there's no way I'm paying for the Verizon service, but there's other GPS based apps for the BBery that would be pretty cool, some that even do mapping against a topo map if you load it in. It would also be nice to have a backup to the Nuvi to use when I'm in our second car, etc.

I spent a fair amount of time a year and a half ago looking for a hack to unlock the chipset, and could not find one. Maybe the state of the art is different now.

There are a couple of things that might be causing confusion.
Only the iPhone 3G (and newer) has a GPS chipset - the original model didn't.

The location software in most mobile phones uses the Javame location services API which lets you pick a variety of ways to get the position (GPS, nearest cell tower, cell tower triangulation etc) depending on what hardware your phone has, what services your provider charges for and what security settings permit.
GPS uses a lot of battery power and can be slow to get an initial position - so you don't necessarily want to use GPS if your application is just looking up which city you are in for a weather forecast.

The iPhone3G also uses assisted-GPS where the initial position is actually found by cell tower triangulation and then that location is used as a starting point for the GPS solution. This greatly improves the startup time and reduces the amount of CPU and so battery power to get a fix.

One big leap forward - the iPhone Javascript API now includes GPS location so you can easily get a position form a web app.
But remember the iPhone (unlike other smartphones) can only run one app at a time - so if you have a GPS tracking application you can't use the phone for anything else while it's running

Another of those unwelcome surprises from Verizon. :-( Interestingly, with the Droid, Google required Verizon to agree NOT to lock up the GPS, but then with Droid if you don't have service you don't have maps. The singular reason to use Verizon is their network, other than that they totally suck. I'm getting close to going with a iPhone, despite ATT's truly lousy network, and keeping a small basic phone on Verizon as back-up for when I really need to be able to use the damn phone.

<tangent alert>

How can we actually compare coverage from one carrier to another once roaming is taken into consideration? I use Sprint and very frequently stray from the defined coverage areas on their map. Most of the time my phone doesn't indicate that I'm roaming so I'm a little confused. I haven't had a cell phone plan in years that charged for roaming service so I honestly don't care who's network I'm on as long as my phone works.

I can only go by my experience. Can't tell you number of times I have been places and I have no problem with my Verizon phone and the guys with iPhones are cursing. My iPhone carrying friends are constantly harping about the lousy service, not just 3G, but 2G as well. <shrug> For those who stick to major metro areas, not as big a problem. OTOH, don't even try to use an ATT phone at a Denver Broncos game, so even then, their system is easily overwhelmed.

Being married to someone who was in the infrastructure business at the time, ATT's system issues are the result of some historical poor business decisions and the various mergers and such that occurred a few years back. The bottom line is that ATT basically stopped upgrading and building their system out at a critical juncture and have never caught up.

I've heard that Sprint's coverage has historically been lacking but I can honestly say that I've always had coverage anytime anyone else around has had coverage. Of course I've only been with Sprint for a few years too.

I work for Sprint, and our coverage is good-same as Verizon's. They both work off of CDMA, and we dont charge for roaming (not sure if Verizon does or not). Nothing is locked out either. I use a BB Curve, but will be upgrading soon, to something with wifi as well.
The BB apps are great-I have bunch of useful ones installed to include weather, news, and live feeds. I have plenty of friends here who have ATT & their service is lacking. Now, ATT doesnt have a large footprint in my area, so I am sure that has something to do with it. But, if you are primarily concerned with staing in the US, I would suggest CDMA, as its more prevalent here. And, the newer BB devices have wifi capabilities, so you can surf & talk.

because roaming agreements generally only apply for voice and SMS, not data services. That's why it matters what network you pick. Also, increasingly, carriers are NOT allowing their phones to roam to save on interconnect fees.