Is there a sim card on my laptop?

I don't recall there being a cellular version of this netbook like the Mini series (210, 311) or the Inspron Mini (9, 10). However, the cellular radios of this era were often 3G or 3.5G HSPA+, both of which are networks the big 3 no longer support and are probably shutdown; check the IMEI# to see (as well as looking up the model of the modem to confirm). For an absolute answer call your carrier... Unless you have Verizon; they refuse anything that isn't "blessed" and locked down to their liking outside of factory-unlocked Pixels (but permalock the VZW sold Pixel bootloader) and iPhones (mainly because Google and Apple can tell them to pound sand and refuse to sell them the phone and have real bite, or at least hurt their bottom line horribly by saying the unlocked Pixel doesn't work on their network and people will switch to get it unlocked from day one), even today. You need an approved device to get past them and the activation phase, and then you need to swap the active SIM over. Verizon does this as a troll toll.

I know with the Dell netbooks with this feature, you had to buy it that way at the time or it was never going to be upgradeable and may have been carrier locked (no slot, SIM card motherboard, or antennas; NOTE: VZW units had SIM-free boards due to CDMA being their go to at the time). The Latitudes were WWAN-Ready for years; now it's an option (not much, enough to get it WWAN-Ready so you know it can be done). The Latitude cards are generally carrier UNlocked, except Verizon. Not too sure about how "open" the Toshibas were, frankly; I know HP offered the 311 with an unlocked card or Verizon at CTO time, but also a few carrier-specific cards which may have been locked. The VZW contract edition Mini 311 was for sure locked and only worked with them unless you replace the card.

If you find it's a 3G class modem, look for a 4G LTE modem like the Sierra modules used in the Dell laptops; these shouldn't have a whitelist for the WWAN module, but it may have come for later Toshiba BIOSes starting with Haswell. The reason you want the Dell modem is they use the stock Vendor ID on theirs (they just print the Dell part number at the absolute worst) and do not require a specific driver like Lenovo (who did it due to BIOS whitelisting which stopped with Broadwell on the Think series, Haswell for the consumer line?? I don't know, I just treat the non-Think products as potentially whitelisted until I can validate with a Dell or HP card), as their cards refuse anything but the Lenovo drivers.

Any particular reason you want to do this? These days you can get a phone plan with hotspot data included as standard; they are just using your standard data "pool" these days unless you pay extra for an extra pool (or a dedicated pool with unlimited). While it seems counterintuitive, having a bigger data plan on your phone is honestly cheaper because, for example, I do not need a lot of data for my phone; but on some providers, if you load up in bulk you can get "hotspot data" which can be interchanged at will for like $5-8 more. It's far cheaper that way for us (and most people with these plans do not need all of the data and can allocate it; the carriers know this) so they make it inexpensive enough for people to pay for extra interchangeable data. Plus with a good unlocked phone (like a Pixel or iPhone, even a 5G Motorola) you have all the bands available and usually end up with a faster hotspot than these cards ever offered being more targeted towards one or two carriers. At the time I write this, the 5G speeds on my factory-unlocked iPhone 12 beat out most hotspots or Sierra wireless cards (though I'm sure factory resetting or updating a "locked" iPhone once carrier unlocked in recovery mode will do the same thing most likely, but require recovery mode to reload the radio firmware). If I need to connect my tablet or a laptop for instance, I just rely on the data in my standard data pool because I do not need 15GB; I don't care if I burn 4-5GB for a few hours to run my tablet on cellular. Essentially what I recommend people who want this do is "cushion" by picking a plan with extra data that you can dynamically use (Example: On a 15GB plan I will usually only use 5-6GB average, maybe 7-8GB; the rest of it can be used at will on my other devices as I see fit). This feature was a byproduct of an era where carriers charged MORE to get a hotspot vs a separate data plan, or you were a business traveler.