Farm alarms and rural coverage: why one network is not always enough
Shed, tank and temperature alarms often depend on a small GSM unit, sometimes in a metal box at the edge of the yard, and what matters is the signal at that exact spot. This guide covers how to test it, where to put the antenna, and which older diallers are exposed to Eir's 3G switch-off.
Why the yard is a hard place for a signal
ComReg's coverage map shows predicted outdoor coverage for each provider at an address, Eircode or location [4][5]. Because it is an outdoor prediction, it cannot show what reaches a dialler inside a steel cabinet [6]. A phone is normally used in the open, so a phone that works in the yard says little about an antenna inside a box. When the Irish Examiner reported on the map in 2019, it described grades from very good to fringe, and said fringe means disconnections are likely [6].
Three things cut signal at the unit:
- Metal. One dialler manual says a unit mounted in or on metal acts as a shield [9]. SimFalcon also says metal boxes can reduce signal [12].
- Centimetres. A 2010 installation guide for a GSM speech dialler says moving the antenna 80 mm can change signal strength markedly, which matters most when the signal is weak [8].
- The network. ComReg's map shows predicted coverage separately for each provider [4], so one network can be weak at an outbuilding down the lane while another is fine at the farmhouse.
Why a single-network SIM can be the weak point
A SIM tied to one network cannot fall back on another if that network is weak at your yard. Both dialler guides list a better antenna position or a different provider as the options [8][9].
A multi-network SIM can register on more than one supported network [13]. SimFalcon says this gives a device a better chance of connecting where a single-network SIM struggles [12], but that it is not a signal booster and does not guarantee the strongest signal [13]. Which network a device uses depends on the SIM service, the supported networks, the device and network policies [13].
The SIM can also fail quietly. A farm alarm may send nothing for months, and both dialler manuals warn that some pay-as-you-go accounts are closed or disabled after a spell without activity [8][9]. SimFalcon says its standard plans are billed annually, or monthly for business volumes, so there are no PAYG top-up expiry issues [14].
Test the signal where the antenna will sit
- Find out how the unit reports. Many older systems send SMS or dial out by voice, and some newer ones use data [12]. For text problems, see the SMS problems guide.
- Test at the antenna position, not at the house. The 2010 guide suggests a phone on the same network as the SIM, held at that exact spot, showing at least three bars. If the phone is on a different network, it says to put the alarm's SIM in an unlocked phone and confirm you can make a call from that position, because the signal indicator alone is not enough. It also says to shut the phone down normally before taking the SIM out, as some networks may lock out a SIM for hours if power is cut abruptly [8].
- Use the unit's own meter if it has one. The GJD manual uses a 0 to 7 scale and says to install only where it reads 2 or more, so check your own unit's manual for its scale [9].
- Compare inside the box with outside it, then trigger the alarm and confirm the message arrives. Some diallers can be set to send a test call or message at fixed periods [8][9].
Where a router or modem shows dBm figures, Teltonika's wiki (written for the modules in its own devices) rates a 4G RSRP weaker than -100 dBm as poor. It rates a 2G RSSI of -100 to -110 dBm as poor, and -110 dBm or weaker as very poor [10]. Other makers' scales may differ.
Placement: what usually helps
- Get the antenna out of the metal. For a unit in or on metal, the GJD manual suggests replacing the antenna with a remote antenna plus cable [9]. SimFalcon says an external antenna, or moving the antenna outside the enclosure, is often the best fix, and that basements and plant rooms can also reduce signal [12][13].
- Fit it where the test was good. The 2010 guide says within 20 mm of the spot where the phone read well [8]. SimFalcon says moving the router or antenna higher, or near a window, often helps [13]. For cable and antenna basics see the weak or no network guide.
- Skip unapproved boosters. ComReg says only repeaters that comply with its standards and carry the CE mark are permitted. It says illegal devices can interfere with the mobile network, will be confiscated where found, and those in possession are liable to fines [7].
- Check the power. One manual describes a power-fail text that is only sent if a backup battery is fitted, and recommends changing that battery at least once a year [9].
3G switch-off: which older diallers are exposed
Eir is switching off 3G from 1 October 2026. Donegal is first, with other counties following in phases over the following weeks [2]. GoMo and Lyca Mobile use Eir's network, so their customers are affected too, and Vodafone switched off 3G in October 2024 [1]. The Irish Times says Three began its own switch-off around the same time as Vodafone [3]. ComReg lists security alarms, fire alarms, GPS trackers, automated electric gates and heating systems among the equipment that may be affected, and advises checking the device or contacting the supplier [1]. Check your operator's own notice for the date in your area.
Eir has contacted customers on 3G-only services directly, and ComReg says the steps may include updating device settings, replacing a SIM card free of charge, or moving to a compatible device [1]. If a message like that mentions an alarm SIM, act on it.
“GSM” on a label does not say whether 3G is there too, so check the data sheet.
| Radio in the unit | Effect of the 3G switch-off | Notes |
|---|---|---|
| 2G (GSM) only | Does not depend on 3G | The Irish Times reported on 24 September 2026 that Ireland has not yet switched off 2G, but that it is coming eventually, further down the line [3]. |
| 3G only | Expect it to lose service once 3G is retired in your area | Needs a 4G version of the unit. A new SIM cannot add a 4G radio. |
| 2G and 3G | May fall back to 2G | ComReg says older devices that connect only to 3G and 2G keep making and receiving calls on 2G, but data services are affected [1]. Check whether the unit reports by data. |
| 4G | Does not need 3G | Confirm 4G support, and the bands, on the data sheet. |
A 3G-only unit needs a 4G version from the supplier. If a monitoring company is involved, tell them before you change anything. See the 3G switch-off guide.
What a multi-network SIM can and cannot do
It can let the unit register on more than one supported network instead of depending on one [13]. It cannot boost the signal or create signal where none exists [13], and it cannot add a 4G radio to a 3G-only unit. A metal box still shields the antenna, whichever SIM is fitted.
To check a site, SimFalcon asks for the Eircode, device type, make and model, and whether the unit is indoors, outdoors or in a metal enclosure [13]. See the farm alarm SIMs page, the coverage page, pricing, or contact SimFalcon.
A note on slurry safety
An alarm that reports a full tank does not make the tank safe to approach. Teagasc says fatal gas levels can occur in the period after agitation commences and advises staying away from the agitation point for the first 30 minutes. It also says HSA/Teagasc guidance does not recommend gas detection systems for farmers [11].
Sources
- [1] ComReg: 3G retirement. Checked 3 October 2026.
- [2] RTÉ News: Eir to begin retiring 3G from October (24 September 2026). Checked 3 October 2026.
- [3] The Irish Times: Eir is switching off 3G (24 September 2026). Checked 3 October 2026.
- [4] ComReg: How to check mobile coverage at a location. Checked 3 October 2026.
- [5] ComReg: Outdoor mobile coverage map and app. Checked 3 October 2026.
- [6] Irish Examiner: New map can point the way in mobile blackspots (15 April 2019). Checked 3 October 2026.
- [7] ComReg: Mobile phone repeaters. Checked 3 October 2026.
- [8] Cooper Security: SD-GSM Speech Dialler guide (PDF, dated 16 June 2010). Checked 3 October 2026.
- [9] GJD: GSM Communicator GJD710 manual (PDF). Checked 3 October 2026.
- [10] Teltonika Networks Wiki: Mobile Signal Strength Recommendations. Checked 3 October 2026.
- [11] Teagasc: Preventing deaths with slurry (11 January 2021). Checked 3 October 2026.
- [12] SimFalcon Ireland: Farm alarm SIMs. Checked 3 October 2026.
- [13] SimFalcon Ireland: Coverage. Checked 3 October 2026.
- [14] SimFalcon Ireland: Pricing. Checked 3 October 2026.
Frequently asked questions
Why does my farm alarm lose signal in the yard when my phone works?
A phone is normally used in the open, while an alarm unit may sit in a metal box with its antenna inside. Test at the antenna position and move the antenna out of the metal before you change anything else.
Will a multi-network SIM fix weak signal on my farm?
It can help where one network is weak and another supported network works at your yard. SimFalcon says it is not a signal booster and does not guarantee the strongest signal, and antenna position still matters.
Is my old GSM dialler affected by Eir's 3G switch-off?
Only if it needs 3G. A 2G-only unit does not depend on it, a 3G-only unit should be expected to lose service once Eir retires 3G in your area (from 1 October 2026, starting in Donegal), and a 2G and 3G unit may fall back to 2G, where ComReg says calls continue but data is affected. The data sheet shows which radios the unit has.
Can I use a pay-as-you-go SIM in a farm alarm?
You can, but dialler manuals warn that some providers close or disable PAYG accounts after a spell without activity, and an alarm may send nothing for months. Some diallers can send a scheduled test call or message to help avoid that. SimFalcon says its plans are billed annually (monthly for business volumes), so there are no PAYG top-up expiry issues.
Questions about connectivity for your equipment? Talk to SimFalcon or ask Engineer Support.