Telecom Informer

    

by The Prophet

Hello, and greetings from the Central Office!  I'm back in the mainland U.S., although I'm finding myself working a lot closer to the Canadian border lately.  Naturally, mobile phone coverage is spotty given the unique Pacific Northwest topography here, and it has led to me carrying two phones: one with a Canadian SIM card, and one with a U.S. SIM card.  You might wonder why, in the year 2021, we haven't really solved the problem of being able to juggle multiple networks on one phone.  The answer is "We sort of have, but it mostly doesn't work and/or isn't available."  Like so many things in telecommunications, it's an exercise in frustration borne of customer hostility and cost controls, and served with a side order of pure, unadulterated spite.

Here in the Pacific Northwest along the Canadian border, it's not uncommon to have no coverage at all from U.S. carriers, and strong coverage bombing in from Canadian carriers for many miles inside of the U.S.  Although mobile carriers are supposed to perform frequency coordination (and the U.S. carriers for the most part do, given the strong FCC regulation in this area), radio signals respect no national boundaries.  This is particularly true near bodies of water where radio will happily skip for miles.  And it's particularly true when Canadian mobile carriers have gone to heroic lengths to cover practically every inch of the Canadian border, including the marine border.  One particular Canadian tower in the Strait of Georgia provides strong coverage all the way to Orcas Island (the home of ToorCamp), where it can be picked up and used from the top of Mount Constitution.

Naturally, given the relatively weak U.S. signal and the relatively strong Canadian signal, you'd think we could just roam on the Canadian networks and be done with it, right?  Well, of course not.  That would make sense, but I work for The Phone Company, who in its infinite wisdom has disabled international roaming on all of our handsets.  I got the backstory.

Last year in the Before Times, a sales team went for a "company retreat" in Puerto Vallarta.  It involved the usual tequila shots and rounds of golf, but also a massive amount of expensive international roaming.  The IT manager, whose budget pays the roaming bill, responded by disabling international roaming plans, which makes total sense for a company whose territory includes a sizable chunk of the Canadian border in which many field locations we service are only served by Canadian carriers.  The company responded by providing a Canadian SIM card, but not a separate device, to those of us with a business need for using Canadian carriers.  The reasoning given was that we can "simply" swap the SIM card.  Naturally, the Canadian SIM cards we were assigned only work on Canadian networks, and don't have any roaming on the U.S. side.

Yes, "simply" swap the SIM card.  All I need to do is take the military-grade case off of my phone, pop out the tiny SIM card using a SIM tool in the dark, swap it with another one, hope that I don't drop either of the cards in the mud and muck on the floor of the truck, wrestle the case back on the phone (hopefully without damaging either the phone or the case), and then maybe I can have phone service.  Minus a couple of fingernails, because that's the average of what I lose when prying off the case.  I'm sure this all makes sense to the bean counters, but I'd really like to see them trying to do all of this before taking pictures of leaking icky-pic from a failed cable in the driving rain at two in the morning which will undoubtedly go in the maintenance backlog, never to be fixed.

So that's what led to me trying to stop the madness and use an eSIM instead.  My handset, a Google Pixel 4a, is equipped with eSIM capability.  Everything old is new again and you can now activate phone service - at least in theory - without physically inserting anything into your device.  Back in the days of analog mobile phone service and CDMA networks, an ESN and MIN pair were all that was needed to authenticate to the network.  Unfortunately, ESNs could be changed (most famously through illegally modified firmware in the OKI 900), and this led to massive fraud.  The industry responded by convincing Congress to pass a law making it illegal to change ESNs.  This, astonishingly, failed to work, although technical countermeasures largely solved the problem right around the time that CDMA 3G networks were retired and the industry converged around 4G.

Introduced in 2017, eSIM is a physical chip on your mobile phone to which a carrier profile can be loaded via software.  The carrier profile is typically delivered via a QR code.  The design is more secure than ESN/MIN pairs of the past because an eSIM is a physical chip that is embedded on a chip (which is about half the size of a Nano SIM card) and generally surface mounted to your device's motherboard.  On the mobile networks, these work almost exactly like a physical SIM card does, save the added complexity of generating QR codes for activation.  And on your device, an eSIM works almost exactly like a SIM card does, except that you can load multiple carrier profiles on the same eSIM (making it very easy to switch between carriers).  In fact, it has become very common for Mobile Virtual Network Operators (MVNOs) specializing in international roaming services to offer service via eSIM only.

At least in theory, activating an eSIM is pretty simple: your carrier sends you a QR code (typically via email) and you scan it with your phone's camera to load their carrier profile to your eSIM.  Although the specification doesn't require support for using a physical SIM and eSIM simultaneously, in practice most eSIM capable phones operate like dual SIM devices (which are very hard to find in the U.S.).  This means that you can pair a physical SIM card with an eSIM and have two networks on one phone.  When one network drops off, the other one can - at least in theory - pick up.  Makes sense, right?

Of course it's not really that simple.  You didn't think it would be, did you?  Neither the U.S. nor Canadian carrier assigned by my employer supports the use of an eSIM on my Android device.  It's an iPhone-only feature.  There is no technical reason for this, but Apple is heavily arm-twisting carriers into supporting eSIM on the iPhone, and evidently no other device manufacturers are doing so.  In any event, only Apple devices are supported on either carrier.  So, I ultimately solved the problem by buying a cheap Chinese-manufactured second phone (made by a company banned from selling equipment to U.S. telecommunications companies) from a questionable website, and putting the Canadian SIM card in it.  And everything works!  Granted, we're only supposed to use company-issued devices for work done with company-issued SIM cards, but for now, none of the security department's mobile device management software works when connected to a Canadian network and the applications I use only check to see whether mobile device management is installed - not whether it's working.  I won't tattle if you don't!

And with that, it's Friday at noon, and it's time to knock off work for the week.  I'm at a campsite where neither Canadian nor U.S. carriers operate, and the barbecue pit is open.  It's time to grill up a nice lunch and then maybe take a nap - erm, I mean "perform inspections."  Stay safe, enjoy your socially-distanced summer, and remember to pay your phone bill!