A while back, I experienced a technical problem with my carrier. As a result, my subscription stopped working. That meant that for everyday I used the internet

A while back, I experienced a technical problem with my carrier. As a result, my subscription stopped working. That meant that for everyday I used the internet connection, I was to be charged 4 euros. The solution was obvious: airplane mode! You know what? It didn't help. They kept charging me 4 euros a day. Then I replaced the APN in the network settings with a fake one and suddenly the daily charges were gone. Airplane mode didn't help, some byte was still passing through. The phone was an android phone. The carrier refunded me right after fixing the problem (which took them a month and half).