Hacker News Reader

Comment by listic | Hacker News Reader

Is Verizon's CDMA network technically compatible with anywhere else in the world? (e.g. so that you can us the same phone in U.S and elsewhere, provided it is not locked)

Specifically, which frequency band does U.S. CDMA use?

View on HN

"Locking" doesn't mean the same thing it does for GSM phones; CDMA phones have a builtin ID which is registered with the network, and there's no SIM card or equivalent to swap out to change that ID.

Sprint and Verizon both use the same CDMA frequencies in the US, and Sprint and Verizon phones roam on each other's networks. But there's no button on your Sprint phone to push to make it a Verizon phone, or vice versa. Sometimes you can get the carrier to do it for you -- the new carrier can choose to activate your existing phone on their network. At least I remember stories of people doing that; I never tried it so can't speak from personal experience.

There is SIM Card equivalent for CDMA technology called R-UIM (Removable User Identity Module). It's commonly used by any CDMA phone outside the US.

I wonder if this CDMA iPhone come with R-UIM card or it have build in ID which register with the network?

No I don't think so. Everwhere else on the world is GSM. That confused me when I first read about USA mobile phones, I wondered what this CDMA thing was.

Worldwide CDMA coverage: http://www.cdg.org/worldwide/

Looking at their map, it's highly misleading, implying there's CDMA 3G coverage in a bunch of places where there is no, or minimal coverage. (They're a trade body promoting CDMA -- what would you do in their shoes?)

CDMA2000 aka EV-DO isn't compatible with W-CDMA, aka UMTS -- the 3G standard used just about everywhere -- and has about 10% of the market worldwide:

https://secure.wikimedia.org/wikipedia/en/wiki/Comparison_of...

Here's a list of CDMA2000 operators. You'll notice a lot in the Americas, especially the USA, plus others scattered elsewhere:

https://secure.wikimedia.org/wikipedia/en/wiki/List_of_CDMA2...

And here's the giant table of UMTS (aka W-CDMA) operators worldwide:

https://secure.wikimedia.org/wikipedia/en/wiki/List_of_UMTS_...

If you're American and don't have a passport, then by all means get a Verizon iPhone 4. But if you expect to travel widely it'd be much more sensible to get a GSM/UMTS iPhone 4, even if it means putting up with AT&T at home. (More sensibly, buy an unlocked one from Apple on a trip to, say, the UK or Ireland: claim back the VAT and buy a micro-SIM on the network of your choice and you're golden.)

> They're a trade body promoting CDMA -- what would you do in their shoes?

I would either tell the truth or quit the job. I take my professional code very seriously.

Very misleading. It highlights Ireland as a CDMA country (there's a trial apparently) However if you had a CDMA mobile phone, it won't work in Ireland.

There are GSM networks in the rest of the world yes, but that is not the only technology outside the US. There are CDMA networks in other countries as well. See: http://en.wikipedia.org/wiki/Cellular_frequencies#Other_Regi...

While it seems not technically right, e.g. CDMA seems to be used here and there around the world, I am reassured in my opinion that if you intend to use your cell phone/modem not exclusively on your home operator's network, you'd better stick to GSM.

Thanks for your links, retroafroman and dboyd! That's exactly what I needed.

No. CDMA is used also outside the US.

* KDDI, Japan's #2 carrier: http://en.wikipedia.org/wiki/KDDI (20-21M users)

* China Telecom http://en.wikipedia.org/wiki/China_Telecom (216M users)

Also others in India too. For instance.

Also, Iraq. Thanks, Darrell Issa!

It's on a different frequency and uses a different communication protocol.

There are a few Verizon phones that are "world phones" meaning they can operate on CDMA and GSM, so you can take them out of the country with you.

I've brought my CDMA phone with me a few times and more or less got by on wifi for data needs (I wasn't going to pay the ridiculous international call fees anyway, last time I did that with my iPhone a 20 minutes of calltime and a few emails cost me over $150!)

And how does that work with the switch to LTE? It seems that AT&T eventually wants to invest in LTE infrastructure, too (but HSDPA can offer at least nearly the speed Verizon’s LTE has to offer at the moment so I don’t think they need to hurry). Will the US converge on one standard? (At least in the sense that building a phone that works both with AT&T and Verizon gets easier?)

It also seems like Verizon really needs to hurry up with LTE (I don’t even know whether you should call it 4G if HSDPA can be nearly as fast) because CDMA doesn’t go very fast. AT&T doesn’t have that same speed gap because they are using UTMS which can go much faster. (The current iPhone is limited to 7.2 Mbps, though.)

There are large CDMA networks in China, not sure whether or not they're compatible with Verizon's (though I would guess they are).

I'm not sure exactly how it works, but Verizon does offer international roaming in a few places (Mexico, etc.). It's nowhere near as good as AT&T's international roaming, but, as other commenters have posted, GSM is far more prevalent outside the US than CDMA.

Independently of the inability to roam in GSM 2G, you may still be able to roam on foreign 3G networks. For 3G, CDMA seems to be ubiquitous, it's mainly a question of at least one of the frequency bands supported by the phone being used in the destination country.

US based sprint uses CDMA.

Reply on news.ycombinator.com