What is the difference between AGPS and GPS in mobiles?

I've been looking at the HTC Touch Diamond and IPhone 3G and I noticed that IPhone 3G only has AGPS while Diamond has both.
I did a search and found out that AGPS is assisted by cellular towers and etc to pinpoint location more precisely.

I'm curious as to whether will using AGPS and GPS incur charges from my network provider?

Answer by manny
if you have an AGPS it needs to be connect to the internet to find you, so yes you will incur data charges if you don't have a data package. If the phone just has a GPS it will still use the internet to load the maps, so either will you will incur data charges.

Answer by niiro13
GPS is simply the standard "takes about a minute or two" to get your location from satellites.

AGPS is the exact same thing, only instead of randomly finding satellites, it finds your approximate location using cell towers and wi-fi networks. Then finds only the satellites within that range and goes out. It's a ton faster.

Therefore, the iPhone and the HTC Touch both have AGPS. There's no GPS and AGPS, because AGPS is the same thing only with an extra feature. If you're in the middle of the desert with no signal, you'll still get your location as the GPS part will still work.

Technically you need a data plan for the iPhone 3G, so while it will incur data charges, it won't matter. Remember that the mobile phones with GPS pretty much don't have built-in maps unless you pay extra for them. Most of them use the unlimited data and download maps onto the phone itself. Therefore, while it does use data to use AGPS, it won't make a difference because you will (or should) have unlimited data.

What do you think? Answer below!

---

Orignal From: What is the difference between AGPS and GPS in mobiles?