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Ajax SIM card Not Working?

Ajax SIM Card Not Working — Here’s the Proven Fix That Actually Works

MELBOURNE HOMEOWNER GUIDE
📅 Last Updated: January 26, 2026

Ajax SIM Card Not Working?
The Easy Fix Guide

Is your Ajax alarm showing no signal? If your SIM isn’t working, your house in Brighton, Toorak, or Richmond might not be safe if your home internet goes down. Here is how to fix it quickly and easily.

⚡ Fast Fix: Which problem do you have?

“No Service”
The alarm has the card inside, but it can’t talk to the phone tower.
Fix: Move the unit or check settings
“SIM Error”
The alarm doesn’t even know there is a card inside.
Fix: Turn off the SIM’s lock code
Grey Icon
You see signal bars, but the internet part isn’t working.
Fix: Check the settings below
App Offline
The signal is good, but your Ajax alarm won’t talk to your phone.
Fix: Turn on ‘Roaming’

1. The Main Fix: SIM Card Settings

Your alarm needs a special “internet address” to work. If this is wrong, your SIM won’t work even if you have full bars. This is the most common fix for Melbourne homes in Richmond and South Yarra.

🛜 What to type in your settings (2026 Table)

SIM Provider What to type in ‘APN’
Telstra telstra.internet
Optus yesinternet
Vodafone live.vodafone.com
Aldi / Boost / Belong mdata.net.au
How to find this in your app:

Open your Ajax App > Go to Devices > Tap your Hub > Tap the Settings Gear > Tap Cellular > SIM 1 > APN. Type the word for your company exactly as shown in our table.

The Old 3G Network Shutdown

In Australia, the older 3G mobile network is being turned off. This means some older Ajax alarms will lose their backup signal. It’s a common issue we see in Richmond.

Older Alarms (2G/3G)

Original models use the older network. While they still work with an internet cable, they won’t have a backup signal anymore. You might need to check our modern alarm systems for an upgrade.

Modern Alarms (4G)

Newer models like the Hub 2 Plus work perfectly. These keep your home in Kew or Beaumaris safe even when your main internet goes down.

2. The Locked SIM Card Fix

The Ajax alarm can’t “unlock” a SIM card by itself. If your card has a lock code on it, it won’t work. You must turn this off using a normal phone first.

1

Use your phone

Put the SIM card into any normal smartphone (iPhone or Android).

2

Open Settings

Go to Settings and find “SIM” or “Security”.

3

Turn OFF lock

Switch “SIM PIN” to OFF.

🛡️

Safety Note

Don’t worry about turning off the lock. Your alarm system is still very safe. The Ajax system is very smart and keeps your data protected.

3. Why Bars Can Lie

Have you ever seen 4 bars of signal but your phone still won’t load a website? This happens to security systems too.

The Signal is Blocked

If your alarm unit is inside a metal box or near big electric machines like solar inverters, the signal gets blocked. It’s like trying to talk to someone while a vacuum cleaner is on.

Too Many People

In busy suburbs like Box Hill or Werribee, too many people using the same phone tower can slow it down. Having two different SIM cards is the best fix.

4. Using Two SIM Cards for Safety

For the best protection in Melbourne, we recommend using two different SIM cards. This means if one brand (like Telstra) has a problem, the other brand takes over.

Slot 1: Telstra

We usually suggest a Telstra card here. They have the best range in suburbs like Frankston and Mornington.

Slot 2: Optus Backup

An Optus card acts as a backup. If Telstra has a problem, your Ajax alarm switches over to Optus in seconds.

5. Will it cost a lot in data?

Very Low Usage

Unlike security cameras that use a lot of data, an Ajax Hub uses very little. It only sends tiny messages to stay connected. Most of our customers find a cheap pre-paid card is more than enough for a whole year.

✅ Pro Tip: Check our maintenance guide for more SIM tips.

6. The “Wait 5 Minutes” Rule

Ajax units take a few minutes to wake up. When you first turn it on or plug in a SIM, it won’t connect right away.

  1. The Hub first looks for your home internet cable.
  2. It then looks for the phone tower signal.
  3. It double-checks a safe connection with your app.
  4. The light turns Green. Please wait at least 5 minutes before trying to fix anything!

Common Questions

Can I use a SIM card from my iPad?

Yes. Any SIM card with data will work. Try to avoid ones that “only” do data if you want the alarm to send you an SMS text message. Check our reliability page for more details.

Why is “Roaming” important?

Some special SIM cards use different towers to keep you safe. To the alarm, this looks like “roaming.” Always make sure Roaming is turned ON in your app settings.

Helpful Links

Still Stuck? Don’t Worry.

If you’ve tried everything and your signal still won’t come back, don’t stay unprotected. Our friendly Melbourne team can come over and fix it for you.

SERVING BRIGHTON, KEW, TOORAK, RICHMOND, CAMBERWELL & ALL MELBOURNE

author avatar
Serhii Sipko – Melbourne Security Installer
Serhii Sipko is the founder of SIPKO Security and a Melbourne-based security installer specialising in high-quality CCTV systems, security alarm systems, intercoms and integrated electronic security solutions for residential and commercial properties. Based in Melbourne, Victoria, Serhii works with homeowners, businesses, property managers, builders and commercial clients to design, install, upgrade and maintain professional security systems. His work focuses on reliable equipment, careful system design, professional installation and long-term performance rather than simply installing the cheapest available security products. Through SIPKO Security, Serhii provides security system solutions including CCTV camera installation, IP security cameras, network video recorders (NVR), security alarm systems, Ajax alarm systems, access control, video intercoms, security system upgrades, repairs, troubleshooting and ongoing maintenance. Serhii has particular experience with professional security technologies and regularly works with leading security brands and platforms used in residential and commercial security installations. He takes a practical approach to selecting security equipment, considering factors such as property layout, camera coverage, image quality, night-time performance, network infrastructure, alarm detection, remote access and the specific security requirements of each property. As a Melbourne security installer, Serhii provides services across Melbourne and surrounding suburbs, including premium residential areas and commercial locations throughout metropolitan Melbourne. His approach is focused on delivering discreet, professionally designed security systems that integrate effectively with the property and provide reliable protection. Serhii also shares practical security advice and technical knowledge through the SIPKO Security website and blog. His articles cover topics such as CCTV installation in Melbourne, choosing security cameras, security alarm systems, Ajax security systems, commercial security, residential security, intercom systems, security system maintenance and improving the overall security of a property. The SIPKO Security blog is written to provide practical information based on real-world security installation experience. Serhii's goal is to help Melbourne homeowners and businesses make informed decisions when selecting security equipment, planning CCTV coverage, upgrading existing alarm systems or choosing a professional security installer. Serhii Sipko is associated with SIPKO Security, a Melbourne security company providing professional security installation and electronic security services. His professional focus is on quality, reliability, technical knowledge and delivering security solutions that are appropriate for the individual property and client requirements. For clients looking for a professional security installer in Melbourne, Serhii Sipko and SIPKO Security provide CCTV installation, alarm systems, intercoms and integrated security solutions for residential and commercial properties across Melbourne, Victoria.