john@kodak.com (John H. Hall) (10/07/88)
In article <telecom-v08i0149m04@vector.UUCP> westmark!dave@rutgers.edu (Dave Levenson) writes: >In article <telecom-v08i0146m03@vector.UUCP>, weinstoc@SEI.CMU.EDU (Chuck Weinstock) writes: >> If I call a number associated with a cellular phone, how does the >> cellular phone operator know which phone to ring and where it is... > >When you dial a number assigned to a cellular mobile telephone, all >of the cell-sites in the mobile phone user's home region broadcast > ...description of how cellular phones work in their "home region" deleted ... Okay, what's a home region? My city? My state? My LATA? Any place in any cell run by the cellular service I subscribe to? While my home and business are stationary, my car is mobile. Assume I live in Rochester NY, and drive to Florida on vacation. If someone in Rochester calls me at my cellular phone: 1. How does it get routed to the cellular system (home region?) through which I happen to be driving? 2. Does the caller have any way of knowing that he's making (and presumably paying for) a long-distance call? The cellular vendors advertise that their phones can be used any place in the country (world?) that has cellular service. That obviously covers the turf of many different cellular systems. Who acts as the "long distance carrier" between cellular systems, and how do they keep the "directory" telling where my cellular phone is RIGHT NOW? -- John Hall, Supervisor: Software Tools Group, Product Software Engineering EASTMAN KODAK COMPANY, 901 Elmgrove Rd., Rochester, NY 14650, 716 726-9345 UUCP: {allegra, rutgers}!rochester!kodak!ektools!john ARPA: kodak!ektools!john@rochester.ARPA
dave@rutgers.edu (Dave Levenson) (10/10/88)
In article <telecom-v08i0154m04@vector.UUCP>, ektools!john@kodak.com (John H. Hall) writes: > In article <telecom-v08i0149m04@vector.UUCP> westmark!dave@rutgers.edu (Dave Levenson) writes: > >In article <telecom-v08i0146m03@vector.UUCP>, weinstoc@SEI.CMU.EDU (Chuck Weinstock) writes: > >> If I call a number associated with a cellular phone, how does the > >> cellular phone operator know which phone to ring and where it is... > > > >When you dial a number assigned to a cellular mobile telephone, all > >of the cell-sites in the mobile phone user's home region broadcast > > ...description of how cellular phones work in their "home region" deleted ... > > Okay, what's a home region? > My city? > My state? > My LATA? > Any place in any cell run by the cellular service I subscribe to? > > While my home and business are stationary, my car is mobile. > > Assume I live in Rochester NY, and drive to Florida on vacation. > If someone in Rochester calls me at my cellular phone: > > 1. How does it get routed to the cellular system (home region?) > through which I happen to be driving? > > 2. Does the caller have any way of knowing that he's > making (and presumably paying for) a long-distance call? > > The cellular vendors advertise that their phones can be used any place in > the country (world?) that has cellular service. That obviously covers > the turf of many different cellular systems. Who acts as the "long > distance carrier" between cellular systems, and how do they keep the > "directory" telling where my cellular phone is RIGHT NOW? What you are asking about is called "Roam" mode or "Roamer Service" by the cellular industry. The "home area" is defined by the cellular service provider. It is the area in which you will receive a call dialed to your cellular number with no other arrangements, and it is also the area in which you do not pay a "roamer surcharge" for the services you use. When your mobile phone is in any area other than your home area, you are "roaming". In this mode, you can originate calls without any special action on your part, if there is a reciprocal billing arrangement in place between your cellular service provider and the company serving the area in which you're roaming. If not, you probably have to call the local mobile operator and establish a temporary account -- generally these are billed to a major credit card. For others to call you, you must give them the "roamer access number" for the area in which you're travelling. They call this number (a toll call to a number in that area) and then dial your mobile number (from touchtone only, please) to call you. You pay the normal charge for incoming calls, plus a roamer surcharge. They pay for the call to the roamer access number. (The roamer access number is often (AAA) 777 ROAM, where AAA is the area code in which the roamer is located.) A few cellular service providers now offer to let the roamer dial a call-forwarding-like feature access code from a roaming area, and have calls forwarded there, by the home system, at the roamer's expense. This will probably become the standard. Cellular companies serving ajoining areas sometimes provide transparent automatic roaming service to each other's subscribers. Here in Northern NJ, we get service from MetroOne, the non-wireline carrier serving the New York City area. Central Jersey is served by Cellular One. I drive between these two areas almost every day. The ROAM icon on my mobile phone blinks on and off as I cross the border between the two companies, but the service is totally transparent. Without any surcharge or special action, I can place calls in either area, receive calls in either area, and drive accross the border while talking, and get handed off inter-system! The inter-system handoff seems to take a few milliseconds longer than normal intra-system handoffs, but is otherwise unnoticable. Ideally, this will become the standard between all ajoining service providers. -- Dave Levenson Westmark, Inc. The Man in the Mooney Warren, NJ USA {rutgers | att}!westmark!dave
brian@umbc3.UMD.EDU (Brian Cuthie) (10/12/88)
In article <telecom-v08i0154m04@vector.UUCP> eckert!john@rutgers.edu (John H. Hall) writes: >X-Administrivia-To: telecom-request@vector.uucp (USENET Telecom Moderator) > >In article <telecom-v08i0149m04@vector.UUCP> westmark!dave@rutgers.edu (Dave Levenson) writes: >>In article <telecom-v08i0146m03@vector.UUCP>, weinstoc@SEI.CMU.EDU (Chuck Weinstock) writes: >>> If I call a number associated with a cellular phone, how does the >>> cellular phone operator know which phone to ring and where it is... >> >>When you dial a number assigned to a cellular mobile telephone, all >>of the cell-sites in the mobile phone user's home region broadcast >> ...description of how cellular phones work in their "home region" deleted ... > >Okay, what's a home region? > My city? > My state? > My LATA? > Any place in any cell run by the cellular service I subscribe to? ^^^^^^^ BINGO ! > >While my home and business are stationary, my car is mobile. > >Assume I live in Rochester NY, and drive to Florida on vacation. >If someone in Rochester calls me at my cellular phone: > > 1. How does it get routed to the cellular system (home region?) > through which I happen to be driving? > > 2. Does the caller have any way of knowing that he's > making (and presumably paying for) a long-distance call? > It's actually much simpler than you would imagine. To call a cellular phone in system that is not it's "home" system, you must dial the "roamer" port. A phone is said to be "roaming" when it has latched on to a system that is not the same as the one programmed into the phone. This is what causes the ROAM light on the phone to be activated. To place a call to a roaming phone, you dial the roam port for the system in which the phone is currently active. You will usually then get a second dial-tone. At the tone, you dial the full 10 digit number of the phone when it is in it's home system. The system then pages the phone and the rest works as normal. It makes more sense when you realize that the phone is programmed with it;s home system ID and it's home NPA and phone number. Thus, let's assume I live in baltimore maryland and my cell phone number is 301 555-1234. If I were in phila and I was on the Cell One system there it's roam port is 215 350-ROAM. To place a call to me while I was in phila you would do the following: 1. dial 1-215-350-7626. 2. wait for tone 3. dial 301-555-1234 4. things work as normal from here. You can see from this example that the long distance charges are paid by the caller. He of course knows it's a toll call when he dials it. Incidentally, the big problem with roaming is that you must know what city I'm in (usually not too big a problem, unless traveling) and you must know which system I am using (since most market areas are served by two systems). There is, of course, a LARGE security problem since the system in which you are roaming has no way of validating your phone's ESN. This is left as an excersize for the ambitious student (ie, don't expect me to spill the beens to the world). cheers, brian