Business SIM Only vs Data SIM — Which Do You Need?
SIM-only plans and data SIMs serve different purposes. Getting the wrong one — or using one where you need the other — wastes money and creates operational problems. Here is how to tell the difference.
What SIM-only means for business
A SIM-only plan provides voice calls, text messages and mobile data — everything a smartphone needs to function as a business phone. You supply the handset; the network provides the connection.
SIM-only plans are typically cheaper than phone-included contracts because there is no handset subsidy built into the monthly price. They suit businesses where staff already have working phones or where you purchase devices separately. See our business SIM-only plans page for more detail.
What a data SIM means for business
A data SIM provides mobile data only — no phone number, no voice calls, no texts. It is designed for devices that need an internet connection but do not need to make phone calls.
Common uses include 4G/5G routers, tablets used in the field, EPOS systems, CCTV, vehicle trackers and WAN backup connections. For a deeper look at data SIM use cases, see our business data SIM guide.
SIM only vs data SIM at a glance
| Feature | SIM Only | Data SIM |
|---|---|---|
| Voice calls | Yes | No |
| Text messages | Yes | No |
| Mobile data | Yes | Yes |
| Phone number | Yes | No (or data-only number) |
| Typical device | Smartphone | Router, tablet, IoT device |
| Roaming available | Usually | Varies by plan |
| Best for | Staff phones | Connectivity equipment |
Which SIM type for which device?
The device determines which SIM type you need. Here is a quick reference:
Smartphones
SIM Only
Voice, data and texts for everyday business use
4G/5G routers
Data SIM
Internet connectivity for offices, events or remote sites
Tablets
Data SIM
Field workers, POS displays, presentations
Failover backup
Data SIM
Automatic WAN failover when broadband drops
When your business needs both
Most businesses with more than a handful of connections end up needing a mix. Phones need SIM-only plans. Routers, tablets and IoT devices need data SIMs. Trying to force one type onto every device either wastes money or limits functionality.
A blended setup might look like this:
Example blended setup
This kind of setup is managed through a single broker, keeping admin simple despite using multiple networks. For data-heavy setups, Three is often competitive on data allowances.
Mistakes and cost traps
Putting data SIMs in phones
You get data but no voice or texts. Staff end up using WhatsApp and workarounds, which is not reliable for business communication.
Using SIM-only plans in routers
You pay for voice and text you never use. A data-only plan on the right network is cheaper and more appropriate.
One data allowance for everything
A phone user who needs 5GB and a 4G router serving an office need very different data levels. Match allowance to device use.
Ignoring coverage per device location
Your router at the warehouse may need a different network from the phones at head office. Check coverage for every device location.
When this page is not what you need
If you already know you need SIM-only plans and want to compare deals across networks, go to compare business SIM-only deals.
If you are looking at eSIM specifically, see our best business eSIM guide.
Frequently asked questions
What is the difference between SIM only and data SIM?
A SIM-only plan includes voice, texts and data — designed for phones. A data SIM provides data only, with no phone number for calls or texts. Data SIMs are used in routers, tablets, tracking devices and backup connectivity equipment.
Can I use a data SIM in a phone?
Technically yes, but it will only provide data. You will not be able to make or receive phone calls or texts via the mobile network. For phones, a standard SIM-only plan is almost always more practical.
Do I need both SIM-only and data SIMs?
Many businesses do. Phones need SIM-only plans for voice and data. Routers, CCTV, POS systems and tablets often work better with data-only SIMs. A mixed approach is normal and often the most cost-effective setup.
Is unlimited data available on business data SIMs?
Some networks offer high or unlimited data plans for data SIMs, though these tend to be more expensive. Check whether you genuinely need unlimited data or whether a tiered plan fits your actual usage more cost-effectively.
Not sure which SIM type your business needs?
A free audit reviews your devices, coverage and usage to recommend the right mix of SIM-only and data SIM plans across the best-fitting networks.