What is the phone doing while it is "searching for service" when it connects to a CDMA network?
Q. What is the phone doing while it is "searching for service" when it connects to a CDMA network? Also, how do network messages (SMS or VM notification) get to CDMA phones? More specifically, how does the network address a specific phone when it's not in a call, since there's no specified control channel? Does it still use the pseudo code sequence or does it just address it by ESN?
A. (By Mark van der Hoek)
Every phone, regardless of technology, has to "find" the network. It has to find the right frequency, decode a control channel of some kind, announce its presence to the network, and be ready to receive a call or to place a call. The real question is not why CDMA phones display this message, it's why the other technologies DON'T, since they have to perform the same basic functions.
In the case of CDMA, it has to get synchronized with the system timing. Oddly enough, it does this by looking for the SYNC channel. Once it's in sync, it moves to the access channel/ paging channel (access channel is where the phone transmits, paging channel is where the network transmits, where it registers (announces its presence - - "Hey everybody! I'm here! Let the party begin!") , then parks itself to wait for further commands.
I suppose it's possible that CDMA phones take longer to acquire the network than other phones, and that's why we see the difference in the display. I don't know what typical times are for acquiring the network.
I've shown a similar photograph before, now here is the story. It was taken by an engineer who wishes to remain anonymous. Mark van der Hoek writes, "This photograph was taken by someone I know. The monopole was in St. Louis. The engineer was driving the network trying to find the cause of one site dropping a lot of calls when he got a call from the NOC (Network operation center) telling him that the site had gone off the air. They wanted him to investigate since he was in the area. He drove over to see what was going on, and that’s when he took the picture."
