The tracker has arrived, maybe it is already tucked behind the dashboard of a company van or a camper, and the last missing piece is a SIM card for the GPS tracker. A phone store is rarely much help, because a tracker never makes calls, yet it needs a connection that runs for months unattended. The short answer: you need a SIM in the right size, with a data plan on a network that has LTE coverage along your routes, the PIN request turned off and the correct APN set. With typical settings, a few megabytes up to a few dozen megabytes a month is enough. SMS and roaming only matter if your use case actually needs them.
It also helps to know what the SIM does not do: it does not make the location more accurate. The tracker calculates its position from satellite signals; the SIM only gets that position to you. We use the Teltonika FMC920, a compact 4G vehicle tracker, as the example for choosing the right card.
Does a GPS tracker need a SIM card?
A GPS tracker does two separate jobs. First it receives signals from GPS, Galileo and other satellite systems and works out where it is. That part needs no SIM, because satellites only transmit and never receive anything from the tracker. Then the position has to go somewhere, onto a map in your tracking platform or into a trip log on a server. For that second step a cellular tracker uses the mobile network, and that is where the SIM card comes in.
Without a SIM, a cellular tracker is not useless, but it turns into a data logger. The FMC920 stores its records in 128 MB of internal flash memory and sends them once it has a connection again. The same applies to dead zones: the trip still lands on the server in full, just later. Without any SIM, though, the data stays in the device until you read it out over a cable, which is no use for live tracking.
Some trackers skip cellular entirely and send over LoRaWAN or Bluetooth instead; that is a separate topic. For classic cellular trackers the answer is clear: remote tracking needs a SIM.
Whether a SIM comes in the box depends on the kind of tracker. Many small consumer trackers for luggage, bikes or pets ship with a built-in SIM or eSIM and a subscription from the maker. You pay a monthly or yearly fee, tracking runs through their app, and you never deal with networks, APNs or data limits. The catch is that you cannot switch network or plan, and when the subscription ends or the service shuts down, the device stops reporting. Fleet trackers work differently. With the FMC920 you insert your own Micro-SIM; the device is not tied to a plan. You choose the network, can swap the card anytime and decide which server receives the data, so you need one: a tracking platform that supports Teltonika devices or a receiver of your own.
GPS tracker SIM card: which networks and sizes work?
Three things have to match: the card size, the radio technology and the settings on the card itself. On size, the FMC920 is clear: it takes a Micro-SIM. Most SIM cards now come as a multi-cut card, so you pop out mini, micro or nano size as needed. Use the micro cut directly rather than a nano SIM in an adapter, because everything in a vehicle vibrates and a shifting adapter is an avoidable point of failure. Teltonika says to insert the card only with the device powered off, meaning external power disconnected and the internal battery unplugged; otherwise the card can be damaged or not detected.
On radio technology, the FMC920 uses LTE Cat 1 and falls back to 2G (GSM) when LTE is not available. The European variant, FMC920-QJIB0, supports LTE bands 1, 3, 7, 8, 20 and 28. That covers the bands German networks Telekom, Vodafone and O2 use for LTE, including band 20 at 800 MHz, which carries coverage in rural areas. For North America the European variant is the wrong choice, since it lacks bands such as 2, 4 and 66 that carriers there rely on. For your plan, this means LTE data must be enabled. Some IoT plans run only on NB-IoT or LTE-M, and a Cat 1 modem will not connect with those cards, even though both sound like “4G.” Do not count on the 2G fallback either, because some countries have already switched 2G off or are in the process of doing so.
That leaves the card itself. The PIN request should be disabled, or you enter the PIN in the Teltonika Configurator, which also shows the status of the inserted SIM. The table below sums up what the FMC920 expects and where setups most often go wrong:
| Feature | What the FMC920 expects | Common mistake |
|---|---|---|
| Size | Micro-SIM | Nano SIM in a loose adapter |
| Radio technology | LTE Cat 1, 2G fallback | Plan limited to NB-IoT or LTE-M |
| LTE bands (QJIB0) | 1, 3, 7, 8, 20, 28 | Device variant built for another region |
| PIN | Disabled or stored in the Configurator | Active PIN, card stays locked |
| Data access | Mobile data enabled, correct APN | Registered on the network but no data session |
Most problems hide in the bottom two rows. A card that works in your phone is not proof that it will work in the tracker, because the phone may have handled the PIN and APN for you without asking.
How much data does a GPS tracker use?
Less than most people expect, but more than position data alone suggests. Usage depends on how often the tracker creates a record and how often it sends. On the FMC920 these are two separate settings. Records are created by time, by distance driven, by a change in heading beyond a set angle or by a change in speed, with different values depending on whether the vehicle is moving or parked. Sending happens on the Send Period schedule, and only once enough records have been collected.
A rough estimate shows the scale. Say your car is driven 90 minutes a day, with a record every 30 seconds while moving and one per hour while parked. That is about 200 records a day. At a generous 100 bytes per record, you get roughly 20 kilobytes a day and about 0.6 MB a month. Those 100 bytes are an assumption for the math, not an FMC920 specification; the real size depends on which inputs and outputs you include.
On top of that comes the cost of the connection itself: setting it up, acknowledgments, retries after dead zones and, if you turn it on, TLS encryption. Teltonika notes that TCP uses more data than UDP because of the extra acknowledgments. What really adds up is over-the-air firmware updates, since a firmware file is orders of magnitude larger than a position record. So add a generous margin to your estimate. For a normally used car tracker, a data plan with 10 to 50 MB a month is usually plenty; you do not need a gigabyte plan like the one on your phone.
You only know for sure after measuring. Run the tracker for a typical month with your final settings and compare against the usage your provider bills. Also find out what happens when you hit the limit: is the connection slowed, cut off or charged at a steep rate? A throttled tracker usually keeps reporting; a blocked one only keeps storing.
Can you use a prepaid SIM in a GPS tracker?
Technically, yes. A prepaid card with mobile data enabled, the PIN turned off and the correct APN works in a tracker exactly like a contract SIM. In Germany you have to verify your identity when activating any prepaid card, and a tracker SIM is no exception.
The weak spots of prepaid lie elsewhere. When the credit runs out, the tracker goes quiet without anyone warning you, because the provider’s low-balance text lands in the tracker, not on your phone. Some prepaid plans also end after a long stretch without a top-up, and a tracker on a trailer that rarely moves can hit those limits sooner than you think. If you go prepaid, set up automatic top-ups, check the inactivity terms and note the phone number and account details.
How do you set the APN on a GPS tracker?
The APN (access point name) tells the tracker which gateway of your provider to use to reach the internet. Without the right APN the card still registers on the network, but no data connection is established. Your SIM provider supplies the correct values; sometimes a username, a password and an authentication type (PAP or CHAP) are part of it.
The FMC920 often handles this for you. From firmware 03.25.15.Rev.32 it has an Auto APN feature that picks the matching APN from a database built into the firmware, based on the inserted SIM. IoT SIMs with their own APN usually need a manual entry: connect the tracker to the Teltonika Configurator on Windows over a Micro-USB cable or Bluetooth and enter the APN, plus username, password and authentication if required, in the GPRS section. The same section holds the server address, port and protocol, which is where the tracker sends its data. Save to device writes the settings to the tracker.
If nothing arrives after that, check in order: Is the tracker registered on the network? Is there a data session? Does it reach the server, and does the platform know the device? The Configurator shows the cellular status in its status window. Be patient: after repeated failed connection attempts, the FMC920 by default waits longer between tries, up to ten minutes, so it does not flood the network. A corrected APN therefore does not always take effect immediately.
Does a GPS tracker SIM need SMS?
Not necessarily. You set up the FMC920 over USB or Bluetooth, and most platforms send commands over the data connection. A data-only plan without SMS is then fine. That matters, because many IoT plans offer SMS only at extra cost or not at all.
SMS becomes useful when you want to talk to the tracker straight from your phone without a platform. The FMC920 understands SMS commands, such as asking for its current position, and can reply to an incoming call with a position text. It can also send records as binary SMS to a server number when there is no data connection. Only a server can read that data, not your phone.
If you use SMS, lock it down. With no authorized numbers entered, the FMC920 accepts commands from any phone number. Set a login and password for SMS commands and enter the numbers allowed to control the tracker.
Will a GPS tracker SIM work abroad?
Within the EU, plus Norway, Iceland and Liechtenstein, consumer plans follow “roam like at home”: your domestic allowance applies there without a surcharge. That is enough for a vacation in a camper. The rule has a fair-use limit, though: if a card spends months mostly roaming and barely uses its home network, the provider may add surcharges after a warning. A tracker in a truck that operates abroad most of the time can produce exactly that pattern. The EU rule does not cover Switzerland or the UK, where costs depend on your plan.
The FMC920 can also react to roaming on its own. Using an operator list, it tells home, roaming and unknown networks apart and applies separate recording and sending values to each. Abroad, you can have it send less often to save data. Up to 50 operators can go on a blacklist, over which the tracker sends no data. Make sure data sending is allowed in the unknown-network mode, or the tracker will go silent on the first foreign network it meets.
IoT SIM vs phone SIM: which is better for a GPS tracker?
A phone SIM, whether a prepaid card or an extra SIM on your existing mobile contract, is the simple route for a single private car. The setup is familiar and roam like at home covers EU trips. The downsides: phone plans are priced for gigabytes, prepaid credit can run out unnoticed, and fair-use rules are written for people, not for devices that stay abroad.
IoT plans are built for devices that use little data and run for years: small allowances at low prices, often a shared data pool across several devices, a management portal and frequently access to several networks in each country. For vehicles crossing borders, that multi-network roaming is the real advantage. Still, check the plan’s country list against your actual routes, confirm it includes LTE rather than only NB-IoT or LTE-M, and remember that the modem must support the bands in the destination country.
A practical rule of thumb: one vehicle and mostly domestic driving, use a phone SIM; several vehicles or regular cross-border trips, an IoT SIM pays off because you see every card in one place.
Where can you buy a GSM GPS tracker?
When you pick a cellular tracker, it pays to think about the SIM at the same time. First check whether the device has its own SIM slot or is tied to a manufacturer subscription, and which card size it takes. Then look at the radio: an LTE Cat 1 modem like the one in the FMC920 needs a plan with LTE data, the device variant has to match the bands in your region, and 2G should not be your safety net. Work out your data needs from the recording and sending intervals, add a margin for connection overhead and updates, and measure in the first month. Decide whether you really need SMS and how the plan behaves abroad. And do not forget the server, because without a platform the positions have nowhere to go.
Once those points are settled, finding the right SIM card for your GPS tracker is quick. If you are looking for a suitable tracker, you can find our models in the GSM Trackers category.