Which Mobile Country Code do all Swiss cells broadcast, and how does a phone recognize that it is camped on its home network?

All Swiss cells broadcast MCC 228; Salt uses MNC 03. The phone recognizes its home network by comparing the broadcast MCC+MNC with the home network identity derived from its own IMSI on the SIM.

The Swiss numbers:

How home-network detection works:

• Every cell broadcasts its MCC + MNC in the System Information on the BCCH
• The phone's IMSI (on the SIM) begins with the home network's MCC + MNC — e.g., an IMSI starting 228 03… belongs to a Salt subscription
• If broadcast MCC+MNC == the IMSI's leading digits → the phone is in its home network (HPLMN); anything else is a visited network and means roaming

Tip: The IMSI is structured, not random: MCC (3 digits) + MNC (2–3 digits) + subscriber number. Knowing this structure lets you read any IMSI's home country and operator — useful in network traces and forensics alike.

Go deeper:

• International mobile subscriber identity (Wikipedia) — the MCC+MNC+MSIN structure and the HNI (home network identity) that the phone matches against the broadcast.