Can a Wireless Burglar Alarm Be Jammed or Hacked? How Ajax Responds
Yes, any wireless alarm can in principle be jammed, and anything connected to the internet can be attacked. The real question is whether the system notices and tells someone. Ajax hubs keep measuring radio noise, move to a clear frequency when it rises, and alert you and any monitoring company. Links between devices are encrypted and authenticated, and a wired Ethernet connection keeps the hub reporting even if mobile and Wi-Fi signals are blocked.
Here is how jamming and hacking work, what UK law says, and which settings and parts make an Ajax wireless alarm harder to defeat.
What does a jammer do to an alarm?
A jammer floods a frequency with noise so genuine signals cannot get through. The aim is to stop a detector's message reaching the hub, or the hub's alert getting out. An Ajax system can use three kinds of radio:
- Jeweller, the 868 MHz link between detectors, sirens and the hub
- Wi-Fi at 2.4 GHz, on hubs that have it
- Mobile data on the hub's SIM cards
Range is a jammer's weak point. Ajax estimates that a pocket-sized unit reaches roughly 5 to 15 metres in open space, and a mains-powered one around 100 metres. Walls cut both. To silence an alarm, it has to cover the right band, from close enough, for the whole visit.
Are jammers legal in the UK?
Not for the public to use. Ofcom states that using any apparatus to interfere with wireless telegraphy is illegal unless authorised, with a maximum penalty of two years in prison and/or an unlimited fine. Supplying non-compliant equipment such as jammers is a separate offence.
Owning one is a grey area. In April 2026 the Department for Science, Innovation and Technology (DSIT) asked for evidence on jammers, noting that the law did not then ban simply owning one and listing home burglary among the crimes where they are misused. There is no official UK figure for how often alarms are jammed.
How does an Ajax hub spot jamming?
Ajax hubs have a Radio interference detection setting. The hub samples noise on the Jeweller band and shows the average in the app; the Hub 2 Plus manual treats -80 dBm or lower as normal. When it detects interference, the hub moves to a free frequency and notifies users and the monitoring station. You can also have it raised as an alarm to every user. Figures below are from the Hub 2 Plus manual.
| What an intruder tries | What the Ajax system does | Setting to check |
|---|---|---|
| Floods the 868 MHz band | Changes frequency and alerts users and the monitoring company | Send interference as an alarm |
| Blocks or removes one detector | Flags it offline after missed check-ins (just under 5 minutes by default) | Check-in interval, 12 to 300 seconds |
| Pulls a device or the hub off the wall | Tamper switch sends an alert | Siren on tamper |
| Cuts the broadband | Carries on over the SIM cards | Channel loss notice, 3 to 30 minutes |
| Cuts the hub off completely | Ajax Cloud raises a hub-offline alarm (about 8 minutes by default) | Hub-to-server polling |
What if mobile and Wi-Fi are blocked too?
The Hub 2 Plus has four ways out: Ethernet, Wi-Fi and two SIM slots, and Ajax lists the channels as working in parallel. The Hub 2 (4G) and Hub 2 (2G) have Ethernet and two SIMs.
Two SIMs on different networks protect you if one network fails, not from a jammer, which blocks every network's bands nearby. A wired Ethernet link to your router is the one path a radio jammer cannot touch, so plug it in. That holds while your broadband arrives by cable, not a 4G or 5G router.
- Keep the hub out of direct view, with a stable signal to every device and at least a metre from the router, as the Hub 2 Plus manual advises.
- For an outbuilding, a ReX 2 range extender can reach the hub over Ethernet through your router as well as by radio.
If your current alarm uses an analogue phone line, check it. BT says that network will be retired by the end of January 2027 and asks anyone with a burglar alarm on the line to contact their alarm provider. Ajax hubs do not use the phone line.
Can an Ajax alarm be hacked?
The radio link is built to resist attack. Ajax says Jeweller uses encryption based on the AES standard with a dynamic key, frequency hopping and device authentication, designed to stop a fake detector posing as a real one.
The weaker point is usually the account. The Ajax app supports two-factor authentication and shows other logged-in sessions so you can end them. The National Cyber Security Centre (NCSC) advises changing default passwords, turning on two-step verification and keeping automatic updates on for any smart device.
The PSTI product security regime, in force since 29 April 2024 according to GOV.UK, bans guessable default passwords, requires a way to report security flaws and makes makers publish how long updates will last. Ajax lists PSTI Schedule 1 compliance on the spec sheets for the hubs, ReX 2, sirens and detectors listed below.
Where do grades and police response come in?
The Hub 2 Plus, Hub 2 and ReX 2 are Security Grade 2, listed against PD 6662:2017 and BS EN 50131, including the part on radio links (EN 50131-5-3). One catch from the Hub 2 Plus manual: Battery Power Saver mode takes the system out of Grade 2.
According to the NSI, police in England, Wales and Northern Ireland respond only to systems meeting National Police Chiefs' Council requirements: fitted by an approved installer to PD 6662, monitored by an approved alarm receiving centre and given a police URN. Three false alarms in a rolling 12 months lose immediate response. Scotland has its own policy. If your insurer asks for a graded or monitored alarm, check your policy wording.
We supply the equipment and do not fit it. We can recommend a qualified installer depending on the job and area.
Which Ajax parts help most?
Prices include VAT. Delivery is extra, and prices can change.
- Ajax Hub 2 Plus, Ethernet, Wi-Fi and two SIMs: £268.10
- Ajax Hub 2 (4G), Ethernet and two SIMs: £228.45
- Hub 2 (2G) alarm panel, Ethernet and two 2G SIMs: £161.53
- Kit 19 S Hub 2 Plus starter kit with key fobs: £478.66
- ReX 2 range extender with an Ethernet port: £158.07
- StreetSiren outdoor siren, alerts if its case is opened: £119.99
- HomeSiren indoor siren: £71.26
- DoorProtect U door contact: £50.76
- MotionProtect U motion detector: £58.84
Brackets and cases are in Ajax accessories and brackets, or browse everything we stock from Ajax.
Our take
Jamming is real, but it is not an off switch. A jammer has to get past the hub's interference detection, the check-ins from every device and, if you have plugged it in, a cable it cannot reach. So connect Ethernet as well as a SIM, set interference to raise an alarm and turn on two-factor authentication. Other wireless alarms we sell, such as Hikvision AX PRO, also use encrypted 868 MHz radio with frequency hopping, so the same habits apply.
Want help choosing? Call 01902 902251, send us a message or visit our Wolverhampton trade counter. Zenith Security Co. has supplied security equipment since 2012, and we ship nationally to England, Scotland and Wales.
Quick questions
Can a phone-signal jammer stop an Ajax alarm reporting?
Not if the hub is also on Ethernet to cabled broadband. Without it, a hub that loses every channel is flagged offline by Ajax Cloud, which alerts users.
Do two SIM cards stop jamming?
No. They cover a network outage. Ethernet is the backup that beats a jammer.
Will an Ajax alarm work after the landline switch-off?
Yes. It reports over Ethernet, Wi-Fi or mobile data, not the analogue line BT is retiring.
Can you install it for me?
No, we are a supplier, not an installer. We can recommend a qualified installer depending on the job and area.
Source: Ajax Systems: what jamming of a wireless security system is; Ajax Hub 2 Plus manual; Ajax ReX 2 manual; Ajax Jeweller; Ajax on PSTI; Ajax account protection; Ofcom; DSIT; GOV.UK PSTI; BT Digital Voice; NSI; NCSC.
