iPhone Roaming... why not?

[Mr. Owl]

Before I picked up my iPhone (back in the Dark Ages of Mobile Communications ) I had a mobile account with T-Mobile. I started on this account with the V360 and then later moved on to the Razor (which I hated - it was bigger and less functional than the V360).

And then I got my iPhone 3G. Hurray!

But coverage, to put it delicately, sucked. At home I had full bars with my T-Mobile phones, but the iPhone had barely any bars and when it lost reception entirely it didn't pick up another network.

This surprised the heck out of me. When T-Mobile coverage failed the phone never failed to find another network and hop on it for continued coverage. Never once.

The iPhone? Just the opposite. It has never once picked up another network. Why is that? It seems a glaring omission in the functionality of the iPhone.

(I apologize if there's been another topic that covers this - I did a brief search and didn't see one.)

 

[Moi un Mouton]

Well I confess I'm guessing here, but when I look in the Network Selection Settings it is set to automatic and I don't have an option to change that. My phone is jailbroken and unlocked. It makes me think that the iPhone in its home country is set to not roam to other networks.

 

[McGiord]

it's the at&t line that will only allow you connect to its network in the usa.
If you unlock it and use a t-mobile sim you may connect to the t-mobile ntwork but i believe it will be limited to connect to edge and not 3g.

 

[TuffLuffJimmy]

Before I picked up my iPhone (back in the Dark Ages of Mobile Communications ) I had a mobile account with T-Mobile. I started on this account with the V360 and then later moved on to the Razor (which I hated - it was bigger and less functional than the V360).

And then I got my iPhone 3G. Hurray!

But coverage, to put it delicately, sucked. At home I had full bars with my T-Mobile phones, but the iPhone had barely any bars and when it lost reception entirely it didn't pick up another network.

This surprised the heck out of me. When T-Mobile coverage failed the phone never failed to find another network and hop on it for continued coverage. Never once.

The iPhone? Just the opposite. It has never once picked up another network. Why is that? It seems a glaring omission in the functionality of the iPhone.

(I apologize if there's been another topic that covers this - I did a brief search and didn't see one.)

I'm going to assume you're on AT&T now, right? Well no cell provider hops from provider to provider. Meaning that if your AT&T phone can't get an AT&T tower signal your phone won't hop on a Verizon or T-Mobile tower. The exception to this rule is many cell providers have contracts with minor small companies that allow them to use their towers in certain areas.

 

[mkrishnan]

It's not, generally speaking, a phone feature that determines whether the phone "roams" to an available partner network (that is, a network with whom your phone company has negotiated free roaming for you). The phone does this if such a network exists. The issue here is that AT&T hasn't chosen to partner with service providers in your area, whereas T-Mo did. So when you're on T-Mobile, you get the roaming and when you're on AT&T, you don't. If you unlocked the iPhone and used it with T-Mobile, it would roam to the partner networks to which you're accustomed.

T-Mobile does this a lot. On the balance side, AT&T has overall a bigger network, AFAIK, in the US than does T-Mobile.

EDIT: Sorry, I got distracted while writing this response. FWIW, as pointed out above, you never jump to a network that is physically incompatible with your own provider -- your AT&T or T-Mobile phone would never jump from GSM to a Verizon CDMA tower. However, it is not true that only small companies are used for partner coverage -- T-Mobile uses AT&T for this purpose extensively, and AT&T's network is, as I already mentioned, actually, I think, larger than T-Mobile's.