Editing Ringback number (section)

==Coin telephones==
[[Narcotics trafficking]] and other criminal activity can use payphones to conduct crimes anonymously, so many payphones are not equipped with a ringer at all, or a quiet "chirper" solid state speaker and designated "No Incoming Calls". All payphones in the [[United States]] must be assigned a telephone number in order to make calls, some can ring or chirp if that number is called. Many [[Payphone#United States|customer-owned coin-operated telephones (COCOT)]] answer the phone at first ring with a built in modem which can be accessed by technicians to report conditions and program function parameters, one programmable function is the number of rings until the modem answers, another is whether to impose an additional charge for incoming calls or even accept no incoming calls at all. Where a payphone does not have any number listed on the unit, the number can be discovered from that phone by calling an [[automatic number announcement circuit]] (ANAC) service or a telephone with caller ID. TelCo owned payphones are generally on dedicated payphone lines which respond to special tones and [[vertical service code|Custom Local Area Signaling Services]] codes such as *5055 for ringback.