Can I put my 4G LTE SIM card in an unlocked 3G phone when travelling in Europe?

[Jordan T]

That's extremely confusing, but you're basically saying they're not cross-compatible? They have to retain CDMA roaming for US-based roaming partners. What I'm still not getting is you're saying LTE is not compatible with CDMA, then how are the current phones working that use the SIM for both CDMA and LTE identification? Also, if TDMA and GSM are two separate systems, how was AT&T selling phones that roamed across both systems while they were transitioning to GSM?

Also, what is the iPad doing now? I know it doesn't need to do voice/text, but it can data roam from Verizon LTE to global GSM, being the first device of it's kind.

Or could the just make phones with two SIM slots, one for LTE and one for global?

The compatibility issue is with voice/text, which, as you note, the iPad cannot do. The existing Verizon LTE phones also cannot do voice/text on LTE, so that answers that question.

AT&T implemented GSM/ANSI interoperability, THAT'S how they did it (and it was rather clunky and they only released two phones). It can be done, but as far as I can tell, Verizon hasn't. If they have, they've got no device using it yet.

The SIM card issue itself is a non issue. The SIM is just memory. The Verizon LTE SIM contains USIM (used in the GSM world) and CSIM (CDMA) applications. But ONLY the CSIM side is ever used for voice/text.

Are you SURE they'll maintain CDMA compatibility for roaming partners? Maybe that's part of their incentive for the "LTE in Rural America" program? Like you noted with AT&T having GSM/TDMA phones, it CAN be done. The curious thing will be to see what Verizon chooses to do. My bets are leaning SLIGHTLY towards them ditching CDMA entirely with VoLTE.

[ItnStln]

My Verizon old SIM card from my Incredible 2 (Global phone CDMA and GSM) actually had the Verizon logo on it. I can also confirm that in some countries, Verizon does have roaming agreements (in Japan, for example, I can jump on the GSM and CDMA networks)

Right, that's how my Storm 2 and Incredible 2's SIM Card worked when I'd travel through Germany and Italy...but it's a bit on the expensive side.

Sent from my ADR6350 using Tapatalk

[ItnStln]

Not likely because the GSM SIM is going to be phased out in the not too distant future.

What's going to be replacing it?

Also, isn't the Droid 4 rumored to be global? I keep hearing conflicting stories. For example, I was told that the GSM hardware is there, just not used at present...seems far fetched to me though.

Sent from my ADR6350 using Tapatalk

[Jordan T]

Also, isn't the Droid 4 rumored to be global? I keep hearing conflicting stories. For example, I was told that the GSM hardware is there, just not used at present...seems far fetched to me though.

The Droid 4 contains a radio controller capable of GSM and UMTS, yes. The device is not approved for operation in these modes, the firmware does not enable it, and there may be other required radio components that are not present for this to function.

[GSMinCT]

Not likely because the GSM SIM is going to be phased out in the not too distant future.

So Verizon is dumping global roaming???

Are you SURE they'll maintain CDMA compatibility for roaming partners? Maybe that's part of their incentive for the "LTE in Rural America" program? Like you noted with AT&T having GSM/TDMA phones, it CAN be done. The curious thing will be to see what Verizon chooses to do. My bets are leaning SLIGHTLY towards them ditching CDMA entirely with VoLTE.

USCC is a roaming partner that they need. And there may be others. Also, I don't think their LTE network is backed up the same way that CDMA 1x is. I don't think LTE has 8 hours of battery back up and a day or more of diesel like CDMA 1x does.

[veriztd]

So Verizon is dumping global roaming???

I didn't suggest that. My point was that GSM will be replaced eventually, if not by LTE then by another standard.

[GSMinCT]

I didn't suggest that. My point was that GSM will be replaced eventually, if not by LTE then by another standard.

But you need GSM to roam globally. Only 40 countries currently use CDMA-based systems. All of Europe, for example, is GSM based.

EDIT: To clarify, 40 countries HAVE CDMA systems. All 210 countries globally, AFAIK, have GSM networks of one form or another, ranging from DC-HSPA+ to GSM with GPRS.

[Jordan T]

USCC is a roaming partner that they need. And there may be others. Also, I don't think their LTE network is backed up the same way that CDMA 1x is. I don't think LTE has 8 hours of battery back up and a day or more of diesel like CDMA 1x does.

While USCC uses a different LTE band, they could roam on USCC GSM, USCC is deploying GSM in some of the areas that need GSM roaming networks. Also, there are other local and national (yes, even AT&T and Verizon can get along if they need to - they roamed on each other for AMPS) GSM/UMTS potential roaming carriers. Finally, VoLTE phones could support USCC's LTE band allowing VoLTE roaming. There's options other than maintaining CDMA. Power backup is easy to move/add too...

[Jordan T]

I just thought of another possibility in a VoLTE world. Verizon could call on Qualcomm to revive their GSM 1x technology they unveiled something like 9 years ago... this was to allow GSM authentication and switching with CDMA2000 air interface.

Of course, there are two problems with this:
1. This requires some type of upgrade (don't know how much) to all the CDMA coverage.
2. Even more importantly, since Verizon LTE will basically overlap their CDMA, any operators Verizon would want CDMA roaming on would have to support CDMA 1x. And, at that point, GSM/ANSI interoperability and CSIM makes more sense - it'd be less work for the CDMA operators.

So, no, I don't think it's likely. But it's a possibility. Honestly, I still wouldn't be at all shocked if VoLTE phones CANNOT do CDMA...

[GSMinCT]

While USCC uses a different LTE band, they could roam on USCC GSM, USCC is deploying GSM in some of the areas that need GSM roaming networks. Also, there are other local and national (yes, even AT&T and Verizon can get along if they need to - they roamed on each other for AMPS) GSM/UMTS potential roaming carriers. Finally, VoLTE phones could support USCC's LTE band allowing VoLTE roaming. There's options other than maintaining CDMA. Power backup is easy to move/add too...

USCC's GSM roamer network it only in the northern parts of NH, VT, and ME. Verizon roams on USCC down east, because their too lazy to build out their own PCS license, and other places nationwide that I'm not as familiar with.

The LTE doesn't cross-support and a lot of those areas don't have USCC LTE.

I know AT&T does roam on Verizon EDGE.

Bottom line: Verizon needs CDMA 1x for roaming.

[Jordan T]

USCC's GSM roamer network it only in the northern parts of NH, VT, and ME. Verizon roams on USCC down east, because their too lazy to build out their own PCS license, and other places nationwide that I'm not as familiar with.

The LTE doesn't cross-support and a lot of those areas don't have USCC LTE.

I know AT&T does roam on Verizon EDGE.

Bottom line: Verizon needs CDMA 1x for roaming.

No, bottom line, Verizon needs a plan. There's no bottom line of them needing anything else.

1. USCC could *easily* expand their GSM roamer network for a large customer like Verizon, that's a non-issue.

2. VoLTE phones could support the full 700 band. The radios aren't there yet, but they're not going to be that far off I'd imagine.

3. Are you telling me there is no GSM carrier in the areas that Verizon roams on USCC? So, some roaming partners might change, big deal. I'm NOT saying Verizon would have VoLTE-only phones. I'm saying they'd have phones that live in the GSM world. GSM/UMTS/LTE phones. If that requires different roaming partners, or for some roaming partners that value their contracts with Verizon to change some technology, so be it.

4. Regarding number 3, ANY option, as far as I'm aware, WILL require CDMA roaming partners to make network changes. And Verizon roaming money is worth a lot to some of these partners. What's easier? 1. Implement GSM/ANSI interoperability (granted I'm not positive this choice requires roaming partners to make any changes but I THINK it does). 2. Implement GSM 1x (GSM backend with the CDMA air interface). 3. Add a GSM roaming network. 4. Add LTE (if you have spectrum Verizon devices can use).

Any of these options require changes on the part of the current CDMA roaming partners (except possibly 1. - I don't know hardly anything about the technical details of such interoperability, especially with LTE Diameter in the equation which is designed with interoperability in mind).

Did you think maybe that's the whole reason behind the LTE in Rural America program? To reduce coverage loss in a world with no CDMA compatibility. Between LTE in Rural America partners and GSM/UMTS roaming partners (including, possibly, an expanded USCC GSM overlay), Verizon does NOT need CDMA. Will CDMA compatibility in some form be their best bet? Only they can decide that, but make no mistake thinking they need it. They don't.

[Jordan T]

One more thought, sorry for the separate post but it's enough later I figure people will have read my last one if following this and might miss this:

1. Verizon, as I showed you, does not need CDMA. They may well decide that CDMA compatibility is their best option, but they definitely don't need CDMA compatibility in a VoLTE world... they've got multiple options, and they're huge.

2. On the other hand, CDMA desperately needs Verizon. This is probably why Verizon managed to get so many rural CDMA carriers to sign up for their LTE in Rural America program. Quite frankly, if you're a CDMA carrier today, you need to be planning to go LTE/VoLTE or die of isolation on both ends. Sure, Verizon will keep their CDMA network up for years. But if you aren't receiving incoming roaming revenue, the equation gets off-balance and your cost of providing national service for your customers skyrockets. Sprint attracts more customers who stick to urban areas in the first place, so Sprint alone won't do it for you. For small CDMA carriers, VoLTE without CDMA compatibility (which, frankly, while I have no insider knowledge, wouldn't surprise me one bit) should be a darn scary proposition if you're not part of the LTE in Rural America program. And if you are part of it, you're basically nothing more than a Verizon network affiliate doing business for Verizon, under Verizon's terms and your name. Look how well that worked out for all the Sprint affiliates when Sprint needed small business help building THEIR network (Sprint then went and gobbled them up). Any LTE in Rural America program participant should, quite frankly, be preparing for a future where Verizon swallows them whole. Any other CDMA rural carrier should be preparing to get cut off from the bilateral roaming traffic that makes their business viable. USCC might stand a chance, maybe. But the very existence of their GSM roaming network seems to indicate to me that they're hedging their bets to a GSM/UMTS/LTE future where their biggest partner is AT&T. And, quite frankly, possibly their new owner eventually...

[GSMinCT]

1. So you are suggesting, that just as Verizon is getting all of their roamer agreements to 3.6mbps EVDO, that they are then going to switch that roaming to 216kbps class 16 EDGE? Riiiiight.

2. From what I understand it's not physically possible. Also, USCC is not going 100% LTE, nor do they have the licenses too, so that's not even relevant.

3. Downeast Maine has extensive AT&T HSPA+ coverage, but some areas they roam on USCC (especially in-market roaming) may not have GSM coverage. Of course, adding GSM coverage would give them coverage in some places they don't have now, depending on the agreements.

4. One option is for Verizon to just build out everywhere with LTE. They have the licenses, it's just a matter of whether they want to do that or not. However, given their current network deployment, they need CDMA roaming.

Strictly speaking, they don't NEED LTE. But their coverage would materially shrink without it.

I doubt the owners of the small carriers are too concerned about Verizon gobbling them up- they own very valuable licenses, and if Verizon wants them, Verizon will pay a pretty penny for them.

I think AT&T will buy USCC, it just makes too much sense. USCC is not now looking seriously at GSM, beyond what AT&T ordered to match up with what they already have, but if AT&T gets them, the CDMA network will be a shadow network to the GSM. Then it might make sense for GSM-based roaming from Verizon.

If AT&T does buy up USCC, and Verizon starts to move away from CDMA, Sprint is screwed, but then again, no one really cares about Sprint.

[Jordan T]

1. Sure, maybe. Roaming is to provide basic voice support. With their LTE in Rural America partners, I could see Verizon finding GSM acceptable for the remaining roaming area. Possibly adding native LTE build-out in areas they deem most important - they DO have a nationwide license.

2. Both upper and lower 700 in one device? Sure, it's physically possible. It raises interference concerns in the radio components, but nothing that can't be engineered around. Just raises cost.

3. Exactly, GSM/UMTS instead of CDMA roaming would change coverage, for better and for worse depending on the area. VoLTE itself will do that. LTE's wide channel will not cover all the rural area CDMA does today. Verizon will need more sites to get the same rural (especially mountain area) coverage.

4. Yup, all pretty much what I said. Except, don't over-estimate the value of rural spectrum licenses. Carriers have plenty of spectrum in rural areas, and it's hard to survive as a rural-only carrier. Sad, but true. The biggest loser, though, if Verizon ditches CDMA is Sprint. Who, from my understanding, has no plans to abandon CDMA voice. LTE is data-only for them.

[johnhere]

I'm glad Verizon plans to ditch cdma voice eventually. Can't wait to experience the volte. Hope it's as good as they say with the call quality.