Elsewhere in the world UMTS is being retired while GSM is being retained because of all the devices (switches, sensors, etc) that use it.

This probably has to do with the historic split between 2G/3G technologies among the major cellular carriers in the US. In the US if you want or need true nationwide coverage (say you are selling a retail IoT device and your customers expect it to work nearly anywhere) you pretty much have to go with AT&T or Verzion and switching a 2G or 3G device between them is impossible. This gives those companies a lot of power to dictate to customers what technologies they can use with their networks.

Since LTE is the lowest common denominator technology between all carriers (and LTE is the only cellular technology with hardware that supports all cellular frequency bands in the US) the cellular market in the US is being pushed very strongly in an all-LTE direction. With the inclusion of Cat-M1 and Cat-NB1 modes in LTE release 13[0], LTE will soon be usable even for low-power IoT devices. AT&T and Verizon are already racing to support those standards on their networks.[1]

[0] https://www.qualcomm.com/invention/technologies/lte/lte-iot

[1] http://www.fiercewireless.com/tech/verizon-at-t-both-claim-l...

The mess that is US mobile protocols and frequencies is what makes me cringe when the rest of the world these days looks to USA for the "latest" in mobile.

Damn it, Nokia had a Symbian phone you could use as a basic desktop for emails and surfing back when iPhone and Android barely did video out (and had to kill the phone screen to do so at least on Android). The mobile world basically came to a standstill, if not went backwards almost a decade, because everyone turned to the odd duck out to lead them into the future...

Kinda weird too considering you can run GSM in the HSPA guard bands without a large degradation of HSPA performance.

Typically HSPA is 5mhz+5mhz FDMA, but the carrier is only 3.6mhz+3.6mhz and can be slimmed to 4.2mhzx4.2mhz on Ericsson equipment. NSN equipment can go as low as 3.8x3.8.

In a slim HSPA situation you can run multiple 0.2x0.2 GSM channels.

LTE I've seen all over deployed in 5mhzx5mhz, but I've never seen the 3mhzx3mhz or 1.4mhzx1.4mhz configurations in the wild (they would overload easy).

Best i can tell, it is for cost reasons.

Non-phone GSM devices are widely operated because of low cost and low data speed needs (most of them just ping a SMS in some direction or other).

UMTS deployments are more likely to be for bandwidth needs, and thus more likely to have moved to LTE setups already.

Sprint has 3x3 deployed on band 26 in some boundary areas of the ibez. There have been some sites spotted in Columbus, Ohio along the ibez boundary that are 3x3 instead of the 5x5 Sprint has deployed everywhere else that's not within 100 km of Canada or Mexico.

That doesn't solve anything as long as your phone supports 2G and falls back to it when 3G/4G are unavailable (i.e. when being deliberately jammed).

Actually only AT&T is scheduled for a 2G sunset right now. Also I think one of the Northern European countries is choosing to maintain the GSM network and then retire UMTS. They're going to have a GSM for IOT and LTE for mobile communications. It's kind of insane. Wish I could find a source...

Less insane when you consider the DDOS attacks from GSM connected IOT devices should be less bad than UMTS/LTE connected ones :) .

2020, where the baseline packet wind of billions of compromised GSM IoT devices is an expected and handled feature of the internet.

And a root nameserver DDOS is just like a coronal mass ejection?

I don't think many GSM carriers allow internet originated, mobile terminated traffic, even for IoT. Mass compromise of IoT is going to be way less trivial for GSM capable devices than things on standard wifi.

What I'm trying to say is that while your quip is entertaining:

a) it's impractical to scan/compromise IoT devices remotely without a stupid design (by IoT standards stupid, btw- not regular internet design- we're talking REALLY REALLY STUPID).

b) I would bet my mortgage that the logic you are presenting was never considered by the relevant carriers. They're not that smart.

Not quite true. Verizon is planning to sunset 2G in 2019 [1], and is making efforts to get customers off 2G before that (similar to what AT&T has been doing). They are also rumored to be planning to shutter 3G in 2021. This leaves only T-mobile and Sprint in the US market providing longer-term 2G support, and their coverage is not great if you need to deploy devices outside major metro areas.

[1] https://www.wirelessweek.com/news/2016/07/verizon-targeting-...

Verizon and Sprint CDMA is technically a 3G technology, not 2G.

> They're going to have a GSM for IOT and LTE for mobile communications. It's kind of insane.

I don't think this is that insane. I doubt there are many devices that only support UMTS, but there are tons that only support GSM, including many in embedded systems that can't easily be upgraded. So by using most of your spectrum for LTE, you get spectrum efficiency, and supporting GSM you can support everything that doesn't do LTE (just not at high speeds).

I think it is KPN in The Netherlands.

Don't lots of phones still send SMS & voice calls over GSM/CDMA? I know VoLTE is appearing, but slowly & only on a couple flagship devices, and quality degrades faster with loss of signal...

Haven't actually seen the signal degradation issues you speak of, probably offset by being able to use a lower band than GSM or HSPA for my carrier.

Carriers have made it a policy to not whitelist imported devices for voLTE. IMEI needs to be whitelisted at carrier AND carrier file installed in phone needs to have support turned on. Either thing missing, no voLTE for you.

EDIT: Forgot to mention, non-voLTE still signals with LTE for incoming calls and SMS, it'll handover to HSPA/CDMA/GSM within about 2 seconds of the signal coming in. Unfortunately I don't have specifics of this process.

Actually i think most SMS is handled via "WAP" these days, meaning that it is carried as a short duration data connection rather than as a special packet in the cells control channel (GSM, dunno about how CDMA implemented it).

the GPRS setting is blocked on featurephones. Still opts for CSD sending there. Newer devices send over 'IMS' (which is voLTE, and also part of HSPA+)

It was a funny loophole to get unlimited SMS on T-Mobile back when they just changed name from Voicestream.

I guess it depends on where in the world one lives.

I'm not American, and thus my phone is free of carrier tampering.

I even learned about the SMS over GPRS (thanks) thing because a relative of mine once owned a phone where we had to turn it off to actually get reliable SMS delivery, as it defaulted to GPRS mode.