The GE Simon XT was the most widely installed residential security panel in North America. Manufactured by Interlogix (formerly GE Security), it powered millions of homes through dealers like ADT, Guardian, Monitronics, and thousands of local alarm companies. But Interlogix shut down permanently in 2019-2020, and the Simon XT is now a discontinued, unsupported product with no future.
If you’re still running one, this guide covers exactly what happened, what risks you face, and how to upgrade without overpaying.
What Happened to GE Security and the Simon XT?
| Year | Event | Impact on Simon XT Owners |
|---|---|---|
| 2000s | GE Security manufactures Simon XT, dominates dealer market | Panel installed in millions of homes |
| 2009 | GE Simon XTi released (touchscreen upgrade) | XT remains most popular due to lower cost |
| 2015 | GE sells security division to UTC (United Technologies) | Rebranded as Interlogix — same products |
| 2019 | UTC announces Interlogix shutdown effective Q1 2020 | No more manufacturing, R&D, or support |
| 2020 | Interlogix ceases all operations | No firmware updates, no security patches, no warranty |
| 2022-2024 | 3G cellular networks sunset across major carriers | Many Simon XT communicators stop working |
| 2026 | Remaining sensor stock drying up, parts scarce | Replacement sensors increasingly hard to find |
GE Simon XT Technical Specifications
| Specification | Simon XT | Simon XTi | Modern DIY Equivalent |
|---|---|---|---|
| Wireless zones | 40 | 40 | Unlimited (most systems) |
| Hardwired zones | 2 | 2 | 0 (wireless-only) |
| RF frequency | 319.5 MHz | 319.5 MHz | Proprietary / Z-Wave / Zigbee |
| Communication | Landline (PSTN) | Landline (PSTN) | WiFi + LTE cellular |
| Cellular module | Optional add-on (3G/4G) | Optional add-on (3G/4G) | Built-in LTE |
| User codes | 1 master + 8 users | 1 master + 8 users | Unlimited users |
| Display | 2-line LCD | Touchscreen | Touchscreen + smartphone app |
| App control | None | None (without Alarm.com add-on) | Full smartphone control |
| Smart home | None | None | HomeKit, Alexa, Google, Z-Wave |
| Video support | None | None | Integrated cameras |
| Geofencing | None | None | Auto arm/disarm by location |
| Reporting | SIA / Contact ID | SIA / Contact ID | Cloud-based push + SIA |
| Manufacturer status | Discontinued (2020) | Discontinued (2020) | Actively supported |
6 Reasons to Replace Your Simon XT Now
| # | Risk | Details | Severity |
|---|---|---|---|
| 1 | No manufacturer support | Interlogix is gone. Zero firmware updates, security patches, or replacement parts from the manufacturer | Critical |
| 2 | Cellular network sunset | 3G modules are dead. Many 4G LTE modules are on borrowed time as carriers migrate to 5G | Critical |
| 3 | Landline dependency | Panel was designed for PSTN. Most homes dropped landlines years ago, leaving only cellular | High |
| 4 | No smart features | No app, no geofencing, no smart home, no video — essentially a 2008-era experience | High |
| 5 | Sensor scarcity | 319.5 MHz sensors are specific to GE/Interlogix. Remaining stock is dwindling with no resupply | Medium |
| 6 | Security vulnerabilities | Older RF protocols are more susceptible to jamming, replay attacks, and interference | Medium |
Your 3 Upgrade Options
Option 1: Switch to a Modern DIY System (Recommended)
The best move for most homeowners. Modern DIY systems are cheaper, smarter, require no contracts, and you own the equipment.
| System | Equipment | Monthly | Smart Home | Contract | Best For | Rating |
|---|---|---|---|---|---|---|
| Abode | $200-$480 | $0-$20 | HomeKit + Alexa + Google | None | Smart home, no-contract freedom | 4.5/5 |
| SimpliSafe | $250-$500 | $0-$28 | Alexa + Google | None | Simplest setup and use | 4/5 |
| Ring | $200-$330 | $4-$20 | Alexa | None | Camera + alarm in one ecosystem | 4/5 |
| Cove | $0-$280 | $18-$28 | Alexa + Google | None | Budget monitoring | 3.5/5 |
Option 2: Keep Panel, Switch to Cheaper Monitoring (Temporary)
If your Simon XT still has a working cellular communicator, you can switch from expensive dealer monitoring to budget alternatives:
| Monitoring Service | Monthly Cost | What You Get | Limitation |
|---|---|---|---|
| Alarm Relay | ~$12/mo | Basic central station monitoring | No app, no smart features |
| Alarm Grid | ~$16/mo | Monitoring + some tech support | Limited by aging hardware |
| Alarm.com add-on | $25-$45/mo | App control + LTE communicator | Expensive, still on dying hardware |
Warning: This is a temporary fix. You’re investing monthly fees into hardware that cannot be repaired or updated. The communicator, sensors, or panel itself will eventually fail with no replacement available.
Option 3: Professional System Replacement
If you want someone to handle the transition, professional-install companies will replace your Simon XT:
| Company | Equipment | Monthly | Contract | Catch |
|---|---|---|---|---|
| ADT | $0-$200 (subsidized) | $28-$60 | 36 months | Long contract, high monthly, early termination fees |
| Vivint | $0 (financed) | $30-$50 | 60 months | Equipment loan = you owe if you cancel |
| Local dealer | $200-$800 | $25-$45 | 12-36 months | Varies widely by dealer |
We generally don’t recommend the professional route for Simon XT replacements. You’ll pay significantly more over 3 years than a DIY system, and you’ll be locked into another contract — the same model that trapped many Simon XT owners in the first place.
3-Year Cost: Simon XT Dealer vs Modern DIY
| Setup | Upfront | Monthly | 3-Year Total | Features |
|---|---|---|---|---|
| Simon XT + dealer monitoring (current) | $0 (existing) | $35-$50 | $1,260-$1,800 | Basic alarm, no app, no smart home |
| Simon XT + Alarm Relay (budget) | $0 | $12 | $432 | Basic monitoring only |
| Simon XT + Alarm.com upgrade | $200 | $35 | $1,460 | App control, still aging hardware |
| Abode (self-monitoring) | $280 | $0 | $280 | Full smart home, app, HomeKit, cameras |
| Abode (pro monitoring) | $280 | $7-$20 | $532-$1,000 | Everything above + 24/7 dispatch |
| Ring (Plus plan) | $200 | $20 | $920 | Alarm + unlimited cameras |
| SimpliSafe (Interactive) | $300 | $28 | $1,308 | Pro monitoring + cameras |
| ADT (new contract) | $150 | $45 | $1,770 | Pro monitoring, 36-mo contract |
The math is clear: Upgrading to Abode with free self-monitoring costs $280 total for 3 years. Keeping your Simon XT on a dealer plan costs $1,260-$1,800 for the same period — with worse features and aging hardware. Even with professional monitoring, Abode saves $260-$800 over a dealer plan.
Step-by-Step Migration Guide
| Step | Action | Details | Time |
|---|---|---|---|
| 1 | Document your current setup | Count all sensors (doors, windows, motion, glass break), note locations, photograph wiring | 30 min |
| 2 | Choose your new system | Abode for smart home, SimpliSafe for simplicity, Ring for cameras | Research |
| 3 | Order matching sensors | Match each Simon XT sensor with a modern equivalent (door, window, motion, etc.) | 1-2 days shipping |
| 4 | Cancel your dealer monitoring | Check your contract for early termination fees. Many Simon XT contracts have expired by now | 1 phone call |
| 5 | Install new system | Mount hub, place sensors in same locations as existing ones, connect cameras | 1-2 hours |
| 6 | Test everything | Walk-test all sensors, verify app alerts, test siren, confirm monitoring (if applicable) | 30 min |
| 7 | Remove Simon XT | Power down panel, remove from wall (or leave mounted as backup siren). Recycle old sensors | 15 min |
Can I Reuse My Simon XT Sensors?
| Simon XT Component | Reusable? | Why / Why Not |
|---|---|---|
| 319.5 MHz wireless sensors | No | Proprietary frequency — incompatible with all modern DIY systems |
| Hardwired door/window contacts | Maybe | Standard hardwired contacts can connect to systems with wired inputs (rare on DIY) |
| Cellular communicator | No | Panel-specific module, likely on sunset network anyway |
| Keypad | No | Proprietary interface, won’t work with any other brand |
| Siren | Maybe | Hardwired sirens with standard voltage may work with adapter, but why bother |
| Mounting locations | Yes | Place new sensors in the same spots — the placement logic is still valid |
The short answer: you’ll need all new equipment, but your sensor placement strategy transfers perfectly. Where you had Simon XT sensors, place your new system’s sensors.
Common Simon XT Problems in 2026
| Problem | Cause | Temporary Fix | Real Fix |
|---|---|---|---|
| “FC” or communication failure | Cellular module on sunset network | Check carrier status, may need LTE upgrade module | Replace entire system |
| Sensor not responding | Dead battery, no replacements available | Try CR123A or similar battery (sensor-dependent) | Replace with modern sensor |
| False alarms | Aging sensors, weak batteries, RF interference | Replace batteries, reposition sensors | New system with better sensors |
| Keypad not responding | Ribbon cable deterioration, age | Reseat ribbon cable | Replace system |
| Can’t reach monitoring | Landline disconnected or cell module dead | Verify phone line or cell module status | Switch to WiFi/LTE system |
| Beeping/trouble codes | Low battery, tamper, communication fault | Clear codes per manual (press 9 + code) | New system |
Simon XT Default Codes and Factory Reset
| Function | Code/Method | Notes |
|---|---|---|
| Default master code | 1234 | Change immediately if still default |
| Default installer code | 4321 | Dealer may have changed this |
| Factory reset | Hold Reset button 10+ seconds during power-up | Erases all programming — use as last resort |
| Clear trouble beeps | Press Status (9) twice, then disarm | Temporary — beep returns if issue persists |
| Enter installer mode | Installer code + pound key | For adding/removing sensors |
Our Verdict: Upgrade Now, Don’t Wait for Failure
The GE Simon XT had an exceptional run — it was reliable, affordable through dealers, and powered millions of homes for over a decade. But Interlogix is gone, the hardware is aging, cellular networks are sunsetting, and parts are disappearing.
Don’t wait for your system to fail in the middle of the night. Plan your transition now:
- Best overall replacement: Abode Smart Security Kit — $0/month self-monitoring, HomeKit/Alexa/Google, geofencing, cameras, no contract. Shop at goabode.com
- Simplest transition: SimpliSafe — 30-minute setup, anyone can use it
- Best camera ecosystem: Ring Alarm — alarm + unlimited cameras under one plan
Whatever you choose, you’ll save money, gain smart features, and actually have a supported system. The Simon XT served its purpose — now let it retire.
Frequently Asked Questions
Is the GE Simon XT still supported by anyone?
Not by the manufacturer (Interlogix closed in 2020). Some third-party monitoring companies and alarm dealers still support existing installations, but there are no firmware updates, security patches, or new parts being manufactured.
Can I still buy GE Simon XT sensors?
You may find remaining stock from third-party sellers on Amazon or eBay, but once it’s gone, there’s no resupply. The 319.5 MHz sensors are specific to GE/Interlogix panels and aren’t manufactured by anyone else.
Will my Simon XT eventually stop working completely?
The panel itself may continue to function as a local-only alarm (siren, entry/exit delays), but communication to monitoring centers will fail once your cellular module’s network is sunset. Without monitoring communication, you have an unmonitored alarm with no phone alerts.
What’s the cheapest way to replace my Simon XT?
Abode with free self-monitoring costs about $280 upfront and $0/month — the cheapest full-featured replacement. Ring Alarm starts around $200 with $20/month for monitoring. Both are dramatically cheaper than continuing with a dealer plan.
Can I reuse my existing Simon XT sensors with a new system?
No. Simon XT uses 319.5 MHz sensors that aren’t compatible with any modern DIY system (which use different frequencies or protocols like Z-Wave, Zigbee, or proprietary RF). You’ll need new sensors, but modern starter kits include the basics.
How long does it take to switch from Simon XT to a DIY system?
Most people complete the switch in 2-3 hours: unbox the new system, place sensors in the same locations as your Simon XT sensors, connect to WiFi, and test. The hardest part is usually canceling your old dealer contract — call them first to check for early termination fees.
Related Resources
- GE Alarm System Review (Full Brand History)
- How to Upgrade Your Existing Security System
- How to Disable Your Home Alarm System
- How to Cancel Your Security Contract
- Honeywell Home Security Review
- DSC Alarm Review
- 2GIG Security Panel Review
- Best DIY Security Systems 2026
Growing up with Law and Order and CSI shows taught Isabelle Landau one thing: if people back then had high-quality home security systems, those series would have been way shorter. In our modern world, technology helps us keep burglars away easily, and this is what Izzy studies and writes about: alarm systems, home security, protection systems, and more.
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