Caller ID is an interesting area and we see a variety of client request regarding this functionality. On analog lines, there is not much room for configuration. Generally this information is transmitted as FSK (i.e. modem tones) in either the SDMF or MDMF format, in the silent portion of the phone company “ring cycle”. For this reason, if you answer an incoming call before the ShoreTel has an opportunity to capture the CID information, you may not see it displayed. [...]