T-Mobile CEO Interested in Sprint Merger...But Not Quite Yet → LTE only, including VoLTE.

It could work. The combined entity should skip CDMA all together - if you want CDMA, go to Verizon. Yes, they will lose customers because of this - tough for those customers, this is a business. The efficiency gained by going LTE only would be significant. There's a lot of unnecessary OpEx associated with CDMA.

This is would be a GSM only company, led by Legere.

ps - are there any basic flip phones that do VoLTE only yet?

Most phones in last several years (Qualcomm-based and iPhone) can do both CDMA/GSM so can help smooth transition away from CDMA towards VoLTE.

There's absolutely no chance you'll see any CDMA added at this point. It's a technological dead end, and even Verizon is working toward getting rid of it as soon as they can transition folks to VoLTE.

I have a CDMA 2000 only flip phone for my Verizon prepaid back up. It's a fairly new Samsung, bought it about 15 month ago and should last with bthe minimal use till 2020.

I haven't seen any LTE/VoLTE flip phones, but I'm sure that, if there's demand, they could be built. The question is whether the carriers want them. If T-Mobile has enough old legacy GSM devices around, such as alarm systems, they might choose to keep a sliver of GSM spectrum going for a while, which would solve the problem, since there are tons of GSM flip phones available, and the people who use them don't usually care about fast data. It's not a permanent solution, but I could see that working for quite a while.

true.