varney@ihlpf.att.com (Al L Varney) (01/28/91)
In article <16476@accuvax.nwu.edu> telecom@eecs.nwu.edu (TELECOM Moderator) writes: >Call Screening sends an interesting message to the person trying to >call a number from which they have been prohibited: [some details removed] >Once added to the directory, calls from *any line* under the same ANI >will be rejected. Example: you have three lines at your home, but all >are billed under the first number. Your first number is presented as >ANI to the network. Calls from your second or third line will also be >rejected. This is a very nice feature, especially the part about >being able to exclude callers no matter what line (within their group) >they use. Obviously if they go out to the corner payphone you can't >stop them. Pat, I'd like more details on your testing of this "feature", since it shouldn't depend on the "ANI", except under very special rules. One reason for this is that, on forwarded calls, ANI is the forwarding party, but you really want the ID of the original calling telephone. All CLASS features rely on the "Calling Party number", which is the telephone number of the originating caller AS KNOWN BY the CO switch. PBX telephones aren't known by the switch, so it uses the "Main" number associated with the PBX lines/trunks -- usually the number listed in the telephone book for the PBX user. Multi-line Hunt groups MAY have lines that have NO telephone number, so the switch uses the the "Main" number associated with the group -- this will lead to the behavior you report. These types of Calling Party numbers are also labeled as "non-unique". Multi-party lines (more than two on a line) may not have a known calling telephone -- the switch labels the Calling Party as "unknown". Bellcore and the industry/ANSI T1 Committee haven't decided on or documented the behavior of Centrex (Bellcore's "business") lines, so they work (or don't work) in whatever manner the switch vendor decided. That's why your "StarLine(?)" service [really "personal" Centrex lines] isn't offered with CLASS -- Illinois Bell can get it on some vendor's switches but not all switches, so they can't or won't tariff it. >If the call you wish to reject did not present ANI or is outside the >LATA (area codes don't matter, but outside the LATA does) then dialing >*60 # the number # will return a recording, "I'm sorry, the number you >wish to add cannot be screened at this time." >Likewise, *66 (repeat dial last number you called) and *69 (return >last call you received) rely on the ANI received. ... ^^^ see "Calling Party" above >If dialing *66 or *69 reaches a busy line then you do not hear the >busy signal. Instead you get a recording ... "Repeat Dial" and "Return Last Call" are probably Ameritech Service Marks for the Bellcore terms "Auto-Callback(AC)" and "Auto-Recall(AR)". Auto-Recall/Auto-Callback attempts initially query the distant number to verify it is a number valid for an incoming CLASS call. The busy/idle status is returned if the number is valid. No call takes place unless/until the line is idle, thus no busy signal. >Other Call Screening tidbits: the number to be screened has to be >supervisable. You can't screen non-working numbers; telco >administrative numbers; police, etc. I cannot screen my distinctive >ringing pseudo-number. As noted, PBX, DID or Centrex systems which >present a single billing number on outgoing calls can have every line ^^^^^^^ See "Calling Party" above >in their system screened by merely entering the billing number. Some >DID numbers leading to a PBX cause some confusion for call screening, >and repeat/return call functions however. The features shouldn't be "confused"; they don't work here because the Calling Party number is not considered "unique", and thus you are unlikely to reach/screen the original calling telephone. Illinois Bell could set the option to allow Auto-Recall to such numbers, but it does complicate the feature documentation to the customer. [You have to explain how you may reach an attendant, not the original caller, and of course the attendant may be unaware of the original call.] >The new CLASS features are a lot of fun and very useful. The big one >missing here at least for a few more months is Caller*ID. I'm told >when we get it here it will also send the ANI of the billing number >when applicable ... not necessarily the actual number being used for >the call. But the rule will be if you can ID it, you can block it. For consistency, of course, Caller*ID (Bellcore's "Calling Number Delivery") uses the Calling Party number, along with the "presentation allowed/restricted" indication. Glad to hear you like the capabilities; a friend in New Jersey that is not a "telecom person" thanked me profusely for the features when I mentioned I had worked on them over the last several years!! She particularly liked the "repeat dial" function, with whatever name Bell Atlantic chose for the feature. One thing Bellcore didn't standardize when documenting CLASS was the NAMES for the features. This will eventually cause real confusion when the people discuss the features or when they relocate to other areas of the country. Al Varney, AT&T Network Systems The above is personal opinion, not AT&T's or its agents. [Moderator's Note: The tests I performed were these: My office has a PBX with sixteen trunk lines. All the trunks have actual numbers assigned to them. The FAX machine has its own outside line/number not connected with the PBX. A few of us have private lines which do not go through the switchboard. From home, I call-screened only the main listed number for our office. Then I used a WATS-extender in my office to call into the PBX from home. I dialed '9' and called my number. The call was rejected. I repeated this from the office the next day, to assure myself I was going out on various trunks -- almost certainly not on the main number (the first trunk) itself. I was even blocked when I used the FAX phone line or some of the private phone lines in our office. Why? I believe it is because every phone in our office is associated with and billed under our main number -- the one that I screened. In the second test, I 'call-screened myself'. That is, I used my first line to tell the switch to screen calls from my first line. When I used my first line to dial my first line, I did not get a busy signal. Instead, I was sent to treatment with the screening message. When I tried dialing my first line from my second line I was *also* screened. Why? Again, I think it was because both of my numbers are billed under the first number. When I did it in reverse, using my second line to screen my second line the results were not the same. My second line was screened from calling my second line, but my first line got through with no argument. I am not sure why. I was unable to get either of my lines to screen calls from my bogus, pseudo-number used for distinctive ringing on the first line. Not that there would be any calls, of course -- there cannot be outgoing calls from that 'line' -- but I wanted to see what would happen. What did haopen was the switch said 'I'm sorry, that number cannot be screened' in the same way it refused to screen numbers not in service or numbers which otherwise do not supervise. Oddest of all were a bunch of numbers in a DID group I tried: Both the main listed number and various internal numbers on the (Rolm-behind-a-few-hundred-DID-trunks) system could not be screened. But IBT would not say 'yes' or 'no' ... the response was 'I'm sorry, that number is temporarily unavailable. Try again in a few minutes.' But no matter when tried over several days, the response was always the same. Finally, if you have been screened, the operator cannot put you through either! It works like our 900/976 blocking here: If I block my phones from 976-whatever, dialing the operator won't help. She cannot connect me. And likewise, if I screen you, then calling the operator *from the line(s) being screened* to ask for an emergency interupt or 'assistance in dialing' will be to no avail. Her calls will be screened also, because the equipment apparently is smart enough to know the number placing the call. Very clever service! PAT]