tim@Athena.UUCP (Tim Dawson) (01/12/89)
In article <telecom-v08i0193m02@vector.UUCP> ghg@en.ecn.purdue.edu (George Goble) writes: > >I just got off the phone with John Covert. He had information which >said that ATT (when they went to #4 ESS toll switches) was the cause >of the roamer ports going off hook. The #4 ESS only allows a one-way >connection until the remote end goes off hook. To provide some added information, this is referred to as answer supervision in the telephone industry, and must be known and programmed in both the Cellular switch and the serving CO. The "off-hook" on the roamer port is actually generated in the Cellular switch, not by Bell. The reason for this is that due to the connection only being one way initally, if the Cellular switch does not return Early Answer Supervision (I.E. when the switch Connects as opposed to a mobile phone answering), the audio path from Bell to the Cellular system is never established and the dialed digits never make it to the Cellular system which then times out and fails the call. Answer supervision is NOT the same thing as an off-hook condition. Answer supervision typically consists of a wink being returned to th C.O (E&M signalling at least) by the Cellular system and is totally irrelevant as to whether the Cellular switch is actually connected to and "listening to" the trunk circuit. The primary reason that Bell uses this is probably just as likely to be to increase billable revenue as it is to prevent toll fraud. Bell feels that they have every right to bill for a call (local or long distance) which terminates to a Cellular system roamer port since they ARE passing audio and the call is utilizing their facilities for a period of time (while you dial the mobile number after receiving the second dial tone). Hopefully someday the Bell companies will agree to exchange billing information with the Cellular carriers and then what is known as Calling Party Billing (where the person who called eats the entire bill INCLUDING the cellular air time, instead of just a local call or whatever, just like a normal long distance land-land call) will be possible. Then whenever that jerk salesman trying to sell you widget X of a wrong number comes in, you could rest comfortably knowing that you won't have to pay for it! tad (First posting, so no signature yet!)