Pages: Getting a Call

Okay, your phone's now registered with your local system. Let's say you get a call. It's the F.B.I., asking you to turn yourself in. You laugh and hang up. As you speed to Mexico you marvel at the technology involved. What happened? Your phone recognized its mobile number on the paging channel. Remember, that's always the forward control channel or path except in a CDMA system. The mobile responded by sending its identifying information again to the MTSO, along with a message confirming that it received the page. The system responded by sending a voice channel assignment to the cell you were in. The cell site's transceiver got this information and began setting things up. It first informed the mobile about the new channel, say, channel 10 in cell number 8. It then generated a supervisory audio tone or SAT on the forward voice frequency. What's that?