The SIM800L seems to be a Quad-band GSM module with GPRS.

So yes it's only 2G, but you've got the potential for SMS and maybe even 512kbps data. No idea about an audio channel (voice calls).

Whilst 2G is old, it's supprisingly battle tested and goes through walls quite well. A year ago we were told to expect the phasing out of 3G networks and to expect carriers to expand 4/5G with 2G as fallback.

Also, you gotta bear in mind, this module can be bought for £5. Getting a PCI-E 2/3/4G micro-pci card for my laptop is priced at closer to £200, so this is a great starting place. Expanding to a module that supports multi-networks either later or as an upgrade wouldn't be overly difficult - this is just a super cheap way of being able to test with real SMS, real networks and real recipients.