why is a CDMA phone still required on Verizon

Vger SD

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I have been looking for an answer to this question for a while. Verizon is phasing out 3G (and most others have already phased this standard out), and per dozens and dozens of posts I've read, 3g is the last time CDMA and GSM were applicable terms. 4GLTE, again per many many posts and articles, doesn't use CDMA or GSM encoding methods (it's TDMA, but a different implementation than GSM per several articles). In spite of this, you still need a CDMA capable phone for Verizon network compatibility. It looks like most model phones are "GSM Only" (not the most popular models, but a large majority of phones not sold by Verizon, especially ones primarily sold unlocked). This is again confusing. Most networks no longer support 3G, 3G is the last time GSM and CDMA are relevant, but most phones are still GSM only, or both CDMA and GSM compatible (no new CDMA only phones as far as I can tell).

So if CDMA and GSM are not relevant, why are the terms still used, and if a phone is 4G LTE or 5G compliant, and has Verizon band compatibility, why is CDMA phone still needed for Verizon network?

I've done many searches, many terms and parameters, and nothing answers this question. I can imagine some answers, but I can't find any verification of any of several theories.
 
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L0n3N1nja

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It isn't. Verizon is shutting down their CDMA network at the end of this year.

It was supposed to be shut down in 2020 but they delayed it possibly due to the pandemic.

As to the topic of this post any phone that won't work with Verizons HD Voice over LTE still relies on CDMA to make calls. If Verizon hasn't certified a particular phone to work with voice over LTE and it doesn't have CDMA it won't make calls. I don't know how friendly Verizon has gotten in recent years with unlocked phones but I know until a few years ago most wouldn't support voice over LTE. Concern that a phone won't work is what keeps me buying Verizon branded phones.
 

Laura Knotek

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It was supposed to be shut down in 2020 but they delayed it possibly due to the pandemic.

As to the topic of this post any phone that won't work with Verizons HD Voice over LTE still relies on CDMA to make calls. If Verizon hasn't certified a particular phone to work with voice over LTE and it doesn't have CDMA it won't make calls. I don't know how friendly Verizon has gotten in recent years with unlocked phones but I know until a few years ago most wouldn't support voice over LTE. Concern that a phone won't work is what keeps me buying Verizon branded phones.
Samsung definitely works on Verizon factory unlocked. I have S22 Ultra from Samsung and unlocked firmware, not Verizon firmware.
 

swebb

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This confuses me also. There are unlocked phones that are 100% compatible, spec-wise, that VZ doesn't support. I think there is some secret sauce, that they call provisioning, that makes it difficult.

In any event, 99.9% of recent unlocked phones (that support US frequencies) can be activated by a simple sim swap on TMobile and AT&T. Not so on VZ. There must be some legacy holdover in their system from the CDMA days that makes it difficult.
 

Mooncatt

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The unlocked phone issue has been discussed a fair bit in Asus ROG phone threads because their phones are notoriously unable to be used with U.S. carriers like Verizon. The only possible exception is the newest version, but requires special steps to trick the phone and get it fully functional.

From what I've gathered reading through those threads is the U.S. differs from the rest of the world in how Voice over LTE (VoLTE/HD calls) is handled. Apparently phones have to be specifically certified to work on a given network, and many companies don't want to spend the money on testing and such to get that certification even if the phone has the right frequency bands.

I think the reason TMO was traditionally unlock friendly was related to them being a German company. Just speculation on my part, but probably along the lines of they are able to have phones work in Germany without certifying and they are able to apply that rule across their entire network (effectively bypassing the U.S. requirement).
 

L0n3N1nja

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Samsung definitely works on Verizon factory unlocked. I have S22 Ultra from Samsung and unlocked firmware, not Verizon firmware.

Yeah, but Samsung already makes their phones compatible globally for all networks so I'd expect theirs to work unlocked. A phone manufacturer that doesn't design devices for Verizon isn't guaranteed to be supported or have the right bands.
 

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