> Having random public phones roam onto your rouge cellular network is a public safety risk So don't let other people on it. Fun story: I worked for a company

> Having random public phones roam onto your rouge cellular network is a public safety risk So don't let other people on it. Fun story: I worked for a company in the UK making GSM picocells with IP backhaul. One day, due to a misconfiguration, we had a lot of confused people from other offices in the building wondering why their phones were roaming onto a Canadian cell network thousands of miles across the Atlantic. Oops.