Heh. movistar in San Diego!
 

I'm in the Point Loma district of San Diego, California on holiday this week and I was amused when one of my phones grabbed onto movistar. I thought perhaps it was an urban network but it's actually service from Tijuana, Baja California, Mexico that I'm getting.

Tijuana is only about 15 km away but still, I would expect the service to be unreceivable here. I certainly can't receive US coverage at any distance from the US-Canadian border, except in rural areas. San Diego-Tijuana has 6 million people, not exactly rural.

Anyway, trivial, but entertaining. I can add one more country to the list of ones I've been registered to on a cell phone (.ca, .us, .uk, .ch, .de, .at, .li and now .mx).

Jim

Here in Europe it's something quite normal at border places, no matter if it's an urbanized or rural area. Expecially when operators use 850/900 MHz networks, it's quite normal that they go beyond borders...

yes, and they even force this by putting huge towers close to the border to catch poor people getting on roaming unrecognized...

Except in rural areas where there is no coverage on the other side of the border, Canadian and US carriers certainly attenuate their signal as much as possible near the borders. I couldn't get reliable AT&T or T-Mobile coverage at a hotel on Front Street in Niagara-on-the-Lake, Ontario, only two blocks from the Niagara River, a couple of weeks ago. To get movistar here (indoors!) is astounding.

We live in San Diego and if we go hiking near the Light House in Point Loma we get a message on our Verizon phones that says "Welcome to Mexico" etc. We have to be careful if we make a call not to pay Mexico Roaming. Point Loma is pretty far from the border too.

Depending on your phone, you can set it to manual network selection, which will solve the problem (and create a new one, depending on the provider, as there'll be no national roaming either).

Isn't there zero danger of an inadvertent outgoing call, as the dialing codes are different in Mexico, and the standard 1+area code +7 digits would not go through?

You should always set up your numbers with the + sign, followed by country code and number so they will work anywhere (such as +12125551212 or +491722222222). It's true, by omitting the GSM-standard plus sign, they might not work in Mexico, but that's no guarantee they won't call something else instead.

Motel75:

You are probably correct. I never tried making a call when the phone roamed to Mexico. This area has a number of hiking trails and cliffs. My bigger fear was not being able to make a call in the US if we were inadvertently set to roaming. FYI, our carrier is Verizon.

I did state there was little danger of an inadvertent "outgoing call". An inbound roaming call is probably more likely.

In Detroit, most Canadian contract phones from neighboring Windsor include Metro Detroit in their coverage area. You can also get a true Rogers signal as far back as Comerica Park which is probably two miles in. My personal feeling is that they should allow this cross-over signal, but too many people call and try to reverse charges because they are too clueless to see what carrier they are on.

In southern Helsinki, Finland, phone can sometimes switch to estonian carrier.. Distance is more than 70 kilometres. Signals can pass over the sea quite well...

Doesn't GSM have a 35-km limit for the signal?

Normal GSM has about 35km limit, but some operators are using coastal/ rural areas etc. technology called "extended cell-feature", which can make 2-3 times longer range..

Btw. In Australia they have launched 200km range 3G.. Australia Gets 200km Wide 3G Cell Sites

on holiday in greece we picked up 2G and 3G signals from Malta - which is nearly 1000km away on some days! -- and on one day 2G from Lybia, 1300km distance, Quite impressive.
Of course you are not able to register to the network as the runtime of the signals it too long but you can see these operators on the op search.

Chris

If it's 1000km away only on some days, where is it the rest of the time? ;) I always knew Malta was just a floating ship!

I think the effect that you describe is due to 'tropospheric ducting' which typically occurs over large bodies of water. I guess it is the same effect that allows you to pick up FM radio signals from across the sea when there are just the right atmospheric conditions.

yeah, my sentence was a bit messed up. Of course Malta is always 1000km away - but you can not always pick the signals. Only if there is a duct as you already described.