Two carriers on the invoice, one core on the network
On 21 October 2026 Orange went nearly ten hours without mobile service across France after a failure in its mobile core; fibre, by contrast, held up. If the plan B for your eight sites is a SIM card, that day you did not have eight backups: you had one. We explain why physical route diversity does not cover this failure, how to read each router's PLMN code in ten minutes to find out which network it is really registered on — and what that code does NOT answer — why Spain has fewer independent cores than the invoices suggest (Orange and Yoigo are one group on a single Ericsson core; Digi has its own core but shares radio with Movistar), and why failover that watches whether the link is "up" never notices a core outage.