They are switching off 3G, and your backup link was 3G

On 4 November, Movistar extended to five more municipalities in Cádiz a shutdown that had begun in Barbate in mid-October. On 16 November it reaches Castro Urdiales. This is not a fault, there is no incident notice and it will not show up in your monitoring: it is 3G, being switched off. The uncomfortable question is not when it reaches your province — nobody has published that calendar — but this one: which technology is your backup modem on right now? If you do not know, you do not have a backup: you have a device with a green light.

We are network integrators, not a mobile operator: we sell neither SIMs nor coverage, and there is nothing for us to sell on the back of this news. We are writing it because the 3G shutdown belongs to a rare category of change: the kind announced two years in advance that still catches people out, because it does not touch what you use every day — it touches what you keep for the bad day.

What has already happened, with the town names in

The pilot is running in 14 municipalities across two provinces. In Cádiz: the capital, Barbate, San Fernando, Puerto Real, El Puerto de Santa María and Rota. In Cantabria: Camargo, El Astillero, Ribamontán al Mar, Piélagos, Medio Cudeyo, Santa Cruz de Bezana, Villaescusa and Castro Urdiales. Between the two provinces some 250 base stations are being disconnected, and what goes off is 3G in the 900 MHz band — where Telefónica holds 2×14.8 MHz — keeping part of the spectrum so that 2G stays standing. Then comes the rest: around 20,900 radio sites through 2027. The two publications that have given the list agree municipality by municipality; a third also mentions Santander, but places it in the December phase rather than the pilot. A list signed by the operator we have not found at all.

That is precisely the operational difference from the copper shutdown, which did come with a list of exchanges and a date per exchange. Here there is a year — 2027 — and a pilot phase. You cannot plan against a year. And it is worth knowing where the other two stand, because it changes who should be reading this. Vodafone started in 2022 and the sources we checked agree that it no longer runs a 3G network in Spain. MasOrange is in the middle of its own: it announced it in November 2025, started in March 2026 in Zamora and Roquetas de Mar, and has an official end date of 31 December 2027 — although one of the round-ups we checked leaves it at "around 2030", a discrepancy we write down because anyone searching will run into it. So of the three calendars, two end in 2027 and none of them comes down to the level of your street. Which is why this post ends in a test rather than a date.

There is an asymmetry worth having in front of you before making plans: 2G will last longer than 3G, but not by the same amount everywhere. The only concrete date we have found published is MasOrange's, which keeps it as a residual network until 31 December 2030. For Vodafone and Telefónica, the sources we checked say no date has been announced, so assuming your 2G runs to 2030 is your assumption and nobody's commitment. The oldest network holds on because lifts, alarms, meters and telecare hang off it, and because a GPRS modem makes do with far less signal than a data one: that is link budget and narrowband sensitivity, not magic in the 900 band. Mobile World Live reported it with the figure attached: Spain's 2G shutdown is stuck on the challenge of upgrading more than half a million lifts. That is where to look first.

They are not taking away coverage: they are taking away compatibility

This is where almost everyone worries about the wrong thing. The 900 MHz band is not being switched off: it is being refarmed. The same antenna, on the same site, at the same power and with the same propagation physics, stops emitting UMTS and starts emitting 4G in that same band. Coverage does not get worse; in many places it gets better, because 4G at 900 travels further and penetrates buildings better than 4G at 1,800 or 2,100 MHz. What disappears is not the signal: it is the language.

And that turns the engineering question into a completely different one. It is not "does coverage reach my unit?", which everyone can answer by looking at the bars. It is "what can the device I have sitting in there actually speak?", which almost nobody can answer without going to look. A modem that speaks LTE on band 8 stays the same or gets better. A modem that only speaks UMTS loses data, with coverage to spare, on the same shelf, with nothing having moved. And one that only speaks 2G will keep showing signs of life for a long, undefined while, which is worse than it sounds: it will work just enough that nobody looks at it.

Why none of this trips an alert

The mobile backup link is the only piece of your network that is fine right up to the exact moment you need it. The router answers pings, the tunnel shows as up, Tuesday's failover test passes, and the monthly report says "backup link: OK". What almost nobody collects as a metric is the access technology: the line that tells a backup running at 3 Mbps over HSPA apart from one running over LTE. Both report green. Only one of the two still exists after the shutdown.

Nor is there a gradual degradation. A disk warns you with correctable errors before it dies; this does not warn you. On the day, in your area, the router that speaks 4G attaches to 4G and you notice nothing; the one that does not, stops being there. And the worst case is not the router in the cabinet, which at least has somebody looking at it once a month. It is the SIM-equipped device nobody is looking at: the alarm, the fire panel, the card terminal in the site hut, the probe in the chilled store, the controller that sends the count through at six in the morning.

The inventory almost nobody has

Before touching anything, the list. Finance already has the list of SIMs on the invoice; the one needed here is the list of your own kit with a radio inside it, which almost always comes out longer. The third column is the one that stings:

If reading that table you thought "half of this is not mine to answer for", that is the right answer and also the problem: the lift belongs to the maintenance firm, the alarm to the security company, the card terminal to the bank, and the probe was fitted by the refrigeration installer. None of them is going to email you. You have to build the list even though the devices are not yours, because on the day they fail, the call comes to you.

The field in the command that answers it

For the kit you can touch, no tooling is needed. The command is the old one, AT+COPS?, and what matters is the last field of the reply, the one 3GPP TS 27.007 calls <AcT> — access technology. It is in the standard, with the same numbers for everyone. Before reading it, one caveat that prevents a backwards diagnosis: that field is optional — the reply syntax is +COPS: <mode>[,<format>,<oper>[,<AcT>]] — some modules do not emit it, and if the modem is not registered the reply stops at the first field. If the last thing you see is an operator name, you still do not know the technology. The values:

• 0 GSM · 3 GSM with EGPRS → 2G. Still in service; the only published closing date is MasOrange's, 31 December 2030.
• 2 UTRAN · 4, 5 and 6 UTRAN with HSDPA or HSUPA → 3G. This is what is being switched off.
• 7 E-UTRAN → 4G. 9 E-UTRAN in NB-S1 mode → NB-IoT. 11 and 13 → 5G and combined 4G+5G.

If the device will not take AT commands, there are equivalent routes. On Linux with ModemManager, mmcli -m 0 carries the access technology in the status block. On a router with a web interface, the mobile connection status page spells out "UMTS", "HSPA+" or "LTE": if it says HSPA, you are on 3G right now, and you have been all along. One warning so you do not trip: some modems need AT+COPS=3,0 before the query to set the reply format, and each vendor also has its own richer command — on Quectel modules, for instance, AT+QNWINFO gives technology and band. The standard field is the lowest common denominator; the vendor one tells you whether you are on band 8.

For the estate with no console — the SIMs in the alarms, the meters, the lift — the route goes through the operator: ask them in writing for the list of lines with the access technology of each one. They have it, because it is what they see on their network. And asking in writing has one advantage over phoning: it records the date on which you asked.

And there is a second question that field does not answer, and it affects four of the seven rows in the table above: voice. While 2G and 3G were there, a device that could not carry calls over 4G simply fell back to the old network to make them and nobody noticed. When the old network goes off, that fallback stops existing and you need VoLTE — voice over LTE, which runs over IMS and has to be supported by the device and enabled on the line. A modem can hand you an impeccable 7 and still be unable to place a call. The intruder alarm panel, the fire panel, the lift line and telecare terminals are, before anything else, devices that make calls: for those, ask the supplier both things, the technology and VoLTE.

The drill: switch 3G off yourself, on a Tuesday morning

Since there is no calendar by locality, you cannot plan against a date. But you can plan against a test, which is cheaper and happens whenever you choose. It is the same method we time our recovery drills with — the last full one came out at 14 minutes, which is a measurement of ours and not a contractual promise: break things on purpose, during office hours, to find the cracks before chance does. Here the break is trivial to cause and perfectly reversible.

• The list first. Every SIM, with the device that carries it, where it is, and the name of the person who answers for it. If that list does not exist, the drill starts here and takes a good deal longer than one morning.
• Tuesday at ten, not Friday at seven. With people awake, the supplier reachable and the week ahead of you.
• Write down the current state of each modem before touching it. The <AcT> value, the configured network mode and the time. Without that "before", the test proves nothing.
• Pin the mode to 4G only. In the interface it is usually called "LTE only". By command, mind the shortcut: the standard's manual selection (+COPS=1,2,"PLMN",7) is not the same thing — it also pins the operator, disables reselection and leaves the modem unregistered if that PLMN is not there; RAT preference is a vendor command (AT+QCFG="nwscanmode" on Quectel, +URAT on u-blox, ^SYSCFGEX on Huawei). Whatever stays attached will stay attached after the shutdown.
• Leave it a week. A minute is no good: what you are looking for is the thing that reports once a day and did not report today. Whatever stops appearing during that week is exactly what will drop on the day of the shutdown, but with a way back and with nobody shouting.
• A written way back before you start: return each modem to automatic selection, plus the list of the ones you touched. That sheet is what turns a test into a procedure.

And now the "when not to", which is the part nobody who has ever broken something skips. If the modem is the only way into a site — the branch with no fibre, the hut on the estate, the site trailer — do not set it to 4G-only remotely without somebody standing there: if the device fails to attach, you have just lost the route you were going to fix it through. And a whole family that admits no nuance: do not touch the devices that make calls — the lift emergency line, the intruder alarm panel, the fire panel and telecare terminals. If any of them lacks VoLTE, leaving it a week on 4G-only leaves it mute for a week, and that does not show until the day it is needed. Those belong to their maintenance company, with its own regulations and liability: the only thing to do is ask in writing which technology each one is on, whether it carries voice over VoLTE, and keep the answer.

When this is not your problem

The honest thing is to say who this does not affect, even if that shortens the list of prospects. If your SIMs are with Vodafone, this already happened and nothing fell over: that was not luck, it was that your estate already spoke 4G. If they are with MasOrange, you are in the middle of the process: it started in March 2026 and the official end date is 31 December 2027, so this is not a retrospective audit but a warning with a little over a year to run. And if your SIM is with a virtual operator, the network it rides on belongs to one of the three: the shutdown that affects you is that network's, and the first question in writing to whoever bills you is which network your line is on. If your backup is a 4G or 5G router bought in the last few years, you will notice absolutely nothing, with the 900 band working in your favour. And if your site has two fibres from two operators over physically separate routes and mobile is the third leg, this is paperwork: change it when the device is due for renewal. On that case — two operators that are not always two routes — we did the whole sum in two carriers on the invoice, one core on the network.

That leaves the ones it does affect: whoever has a modem bought twelve years ago in a cabinet nobody opens, whoever has SIMs scattered across devices a third party installed, and whoever has a small site hanging off a mobile link they have never measured.

What we do about it

At the sites we manage, the mobile link goes into the SD-WAN policy as one more link, with its weight, its failover rules and its continuous measurement. And we collect access technology as a metric, the same way we collect a disk's temperature, because it is the one that warns about a change that raises no alert. If you want the criteria for when that layer genuinely pays off and when it is spending for the sake of it, it is written plainly in SD-WAN: when it pays off and when it does not.

The other half of the job is communications documentation: making sure the list of SIMs and devices lives outside the router that uses it, with an owner and a review date. An inventory that only exists inside the box that goes down is not an inventory; it is part of the outage.

Our standing thesis is that failure is inevitable and an outage is a design decision. The 3G shutdown is the limit case of that sentence, because here the failure is not even a failure: it is a published date, a planned refarm and an operator doing exactly what it said it would. If that takes a site down, technology did not take it down. Not having opened the cabinet did.

Sources (consulted on 2026-11-10): the start of the shutdown, the phases and the dates — Barbate in mid-October, the Cádiz extension on 4 November, Castro Urdiales on 16 November, Cantabria from December and the rest of Spain through 2027 — are in DPL News' report of 2026-11-09, which is also where the figure of some 250 base stations and the 900 MHz band come from. The figure of around 20,900 radio sites for 2027, Telefónica's 2×14.8 MHz in that band and the slice of spectrum reserved to keep 2G running come from Modernet Digital, 2026-11-09. The list of 14 municipalities, the absence of an official calendar by locality, and the detail that old SIMs will still be able to make calls over 2G although they lose data — with a free card replacement — are from Teléfonos.es, 2026-10-26; that list of 14 matches municipality by municipality the one published by Banda Ancha. DPL News additionally mentions Santander, but inside the December phase rather than the pilot; a list signed by the operator we have not found at all. The status of Vodafone's and MasOrange's 3G, and the 2G dates, come from two trade-press round-ups that do not say the same thing, which is why we report it that way in the body: Evalúa Móvil, updated 2026-10-21 (Vodafone started in 2022 and by the end of 2024 it was already effective in Madrid and Barcelona; MasOrange with full shutdown on 2027-12-31, announced in November 2025 and started in March 2026 in Zamora and Roquetas de Mar; MasOrange's 2G as a residual network until 2030-12-31, with no announced date for Vodafone or Movistar) and Don Porqué, 2026-10-30 (Vodafone "no longer has a 3G network in Spain", Movistar targeting the end of 2027, and MasOrange "around 2030"). Neither is an operator statement. The stalled 2G shutdown and the more than half a million lifts were reported by Mobile World Live. The <AcT> values (0 GSM, 2 UTRAN, 3 GSM with EGPRS, 4-6 UTRAN with HSDPA/HSUPA, 7 E-UTRAN, 9 E-UTRAN NB-S1, 11 and 13 for 5G) are from the public standard 3GPP TS 27.007 / ETSI TS 127 007. The comparative propagation of 900 MHz against 1,800 and 2,100 is radio physics, not a claim about anybody's network; that is why we say 900 is refarmed to 4G and do not mention 5G in that band, which we have not seen backed by any source. VoLTE is not news either: it follows from the fact that, with 2G and 3G off, the fallback to the old network for voice stops existing. We are not a mobile operator and we do not resell SIMs from any of the companies named. Photograph: "HSDPA cellular router", public domain via Wikimedia Commons, original 3,648 × 2,736, cropped by us to leave the manufacturer's brand out of frame and keep the two antennas.