About default modems on each continent, a previous post: T1 Modem Variant Works in Librem 5. Details shown when the little arrow is clicked.
The default Broadmobi modems (from manufacturer’s site ):
BM818-E1 (--> Defaults: Europe)
FDD-LTE:B1/B2/B3/B5/B7/B8/B20
TDD-LTE:B38/B40/B41(120M)
HSPA+/WCDMA:B1/B2/B5/B8
GSM/GPRS/EDGE:B2/B3/B5/B8
BM818-A1 (--> Defaults: North-America)
FDD-LTE:B2/B3/B4/B5/B12/B13/B17/B25/B26/B66
TDD-LTE:B41(200M)
HSPA+/WCDMA:B2/B4/B5
GSM/GPRS/EDGE:B2/B5
BM818-T1 (--> Defaults: Asia, Australia, New Zealand)
FDD-LTE:B1/B2/B3/B4/B5/B7/B8/B28/B66
TDD-LTE:B34/B38/B39/B40/B41(200M)
HSPA+/WCDMA:B1/B2/B4/B5/B8
CDMA:BC0
GSM/GPRS/EDGE:B2/B3/B5/B8
The optional additional Thales (formerly Gemalto) modems (from manufacturer’s brochure and other documents on site). There hasn’t been a verification on these yet by Purism. They’d have a bit slower data but VoLTE support:
PLS8-E (--> Europe)
LTE: B1/B3/B7/B8/B20
3G: B1/B3/B8
2G: 900Mhz/1800Mhz
(Voice Support for LTE via VoLTE (Voice over LTE) and CSFB (circuit-switched fallback))
(33% lower peak transfer rate compared to Broadmobis, DL: max. 100 Mbps)
PLS8-US (--> North-America)
LTE: B2/B4/B5/B17
3G: B2/B4/B5
2G 850/900/1800/1900MHz
(Voice Support for LTE via VoLTE (Voice over LTE) and CSFB (circuit-switched fallback))
(33% lower peak transfer rate compared to Broadmobis, DL: max. 100 Mbps)
Note on South-America based on limited search: BM818 covers bands better. For instance Argentinian, Brazilian, Chilean, Paraguayan and Peruvian networks will benefit more from T1 modem as it covers all the combinations. Bolivian networks on the other hand seem to benefit mostly from A1 modem. If you want to use PLS8-modem, please check first which network you will be using and what bands it has as some operators use bands that are divided between E and A1/US models (often only B4 for LTE).
Note on Africa based on limited search: Algeria, Botswana, Egypt, Ethiopia, Niger, Nigeria, Kenya, Mozambique, Senegal, South-Africa, Tanzania, Zambia, Zimbabwe all have networks that predominantly have B1 band (some B3 and B20 here and there) as well as GSM900Mhz. Therefore the E-models should be the default.
Note on Middle-East based on limited search: Bahrain, Iraq, Israel, Jordan, Kuwait, and Saudi-Arabia (as well as Pakistan and India) may be best served with an E-model modem. Mostly B1 and B3 networks, some B5 and B8 but also B40 in couple of places.
Note on Antarctica based on limited search: No network information found. Ski near the Argentinian base to use GSM or use base wifi (satellite).
If you travel a lot, or live near borders (where you may want to use neighbouring towers), you maybe need to take that into consideration as well (use the aforementioned frequencycheck-site).