What is VPLMN
Quick definition
VPLMN (Visited Public Land Mobile Network) is the mobile network a SIM attaches to when away from its HPLMN (the home carrier's network). In international IoT, the VPLMN choice drives roaming cost, latency, and tech availability (LTE-M, NB-IoT) in each country.
How the VPLMN is selected
When the device powers on in a country where its HPLMN is unavailable, the modem scans carriers and picks based on a priority list stored on the SIM (PLMN selector lists). The home operator or the customer manages these lists from the portal.
Why order matters
If your list puts a carrier with a bad roaming agreement first, you pay more and possibly lose LTE-M. Put your preferred carrier first by coverage and price and you optimize. The list can be tuned per country.
FAQ
Can I change the VPLMN list without swapping the SIM?+
Yes, via OTA SIM Toolkit. Most serious IoT carriers support it at no extra cost.
What if every preferred VPLMN fails?+
The modem falls back to the first available (limited service or any network). To avoid landing on poor networks, restrict the list.
Related terms
What is permanent roaming
Permanent roaming is when a SIM connects continuously (beyond a few months) to a network other than its home carrier, never returning home. In IoT it is the norm, not the exception: a tracker deployed in Mexico can live for 10 years on Mexican networks with a Spanish-issued SIM.
What is Multi-IMSI
Multi-IMSI is a SIM technology that hosts several IMSIs (subscriber identifiers) on a single card and picks one based on country, signal quality, or cost. The device authenticates as a customer of carrier A in one place and as carrier B in another, with no hardware change.
ICCID, IMSI, and IMEI
ICCID identifies the physical SIM chip. IMSI identifies the subscriber on the mobile network. IMEI identifies the device (modem) holding the SIM. Three different identifiers, all three needed to manage an IoT fleet.