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Clarification on Phone Locks and CDMA vs GSM

I am trying to better understand this process here in the US. This represents my (possibly misinformed) understanding of how things work. For purposes of this discussion assume that we are starting with a factory unlocked, GSM and CDMA compatible phone. Moto G6 or Samsung S8 if specifics beyond that matter. And further it will probably be various MVNO's that I would be dealing with here (Republic, Consumer Cellar, etc).

1) There will be no locking to start out. A GSM based plan will use a SIM card. A CDMA plan will probably also require a SIM card but it will be used only in connecting to the relevant LTE network. The CDMA provider will put me on a 'white list' that will allow me to access their network. I assume that this is a reference to my phone ID.

2) If I sign onto a GSM plan and were to simply replace the GSM card with someone else's GSM SIM card, then my phone would now work with this new provider with no other steps on my part or the provider's part. I could even move back/forth at will assuming both plans were active.

3) If I have signed onto a GSM plan, then I can also change to a different (CDMA) plan just like #2 above.

4) If I start out on CDMA, I will need my CDMA provider to take some action before I can change to a different CDMA provider and I will not be able to hop between CDMA providers by simply swapping SIM cards.

How much of this did I get wrong? Thanks.


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All Answers

Best Answer chosen by DaveLeeNC

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Very close.

In reply to: Clarification on Phone Locks and CDMA vs GSM

There is something more to do with GSM systems and phones. If I change the SIM card the "phone" works but for data and MMS (large SMS with say a picture) we have to, most of the time, update the APN.

There's a chance in the near future that CDMA (mostly Sprint) will pass as Tmobile buys them and what happens next is in the news.

CDMA gets the most upset folk because of phones are never "unlocked." You get to deal with having it moved to the new carrier. This alone is such a pain compared to unlocked GSM phones that I learned to get away from CDMA long ago.

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Follow up Question

In reply to: Very close.

Thank you - very helpful.

If I go from 'GSM to GSM' who does the APN thing? Is the the 'from carrier' or the 'new carrier'.

Thanks again.


Collapse -
Who changes the APN?

In reply to: Follow up Question

We do. But if your new carrier has a booth or service center, etc. They usually do it for folk because it can get confusing.

On top of that I am getting ready for an Alexa in my car so I have an UNREAL GSM account just for that. The setup also mandates we install an app.

WHAT? What this means is there are going to be other requirements than we used to know (as you pointed out in your top post) when we change carriers.

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