Miguel_Cruz@um.cc.umich.edu (12/29/89)
My phone number (313-663), certifiably a residence, allows seemingly infinite concurrent call forwards with the regular Michigan Bell call forwarding service. As an added bonus, you can forward it to another number (in a different switch) and forward that other number back to it, and call either, and hear endless clicks as the call gets bounced back and forth, eating up more and more trunks (or whatever they use for interoffice calls these days..). [Moderator's Note: If you are correct in this, then I would say there is a very serious problem there; one that MichBell should correct. You can cross-forward here in Chicago, but the call forwards only once in each direction and rings through. That is, I forward to you and you forward to me: Calls to me ring through on your line regardless of how yours is set, and calls to you ring through on me, regardless of how my line is set. Apparently some information is sent with the forwarded call telling the next switch 'call is already being forwarded, ignore further forwarding and ring as requested', or something like that. PT]
erc@cs.utexas.edu> (12/30/89)
In article <2462@accuvax.nwu.edu> Miguel_Cruz@um.cc.umich.edu writes: >X-Telecom-Digest: Volume 9, Issue 599, message 7 of 9 >and hear endless clicks as the call gets bounced back and forth, eating >up more and more trunks (or whatever they use for interoffice calls I read the moderator's note. Can A forward to B, who then forwards to C, who then forwards to A? This can be repeated ad nauseum -- is the phone company smart enough to pick up on this? Ed Carp N7EKG/5 (28.3-28.5) ...!attctc!puzzle!khijol!erc (home) (512) 832-5884 Snail Mail: 2000 Cedar Bend Dr., #335, Austin, TX 78758 [Disclaimer: The information contained in this message is soley for informational purposes only. Use at your own risk. No warranty expressed or implied.] Score: Noriega: 1 USA: 0 "Good tea. Nice house." -- Worf [Moderator's Note: Good point. Honestly, I don't know in all cases. We seem to have two versions running in Chicago: One says stop the forwarding when the point where *the person presently requesting it* has been reached. In other words, no chain-forwarding. A forwards to B; B to C; and C to A. Calls to A ring through to B regardless of B's setting; calls to B ring through to C regardless of C's setting; and calls to C ring through to A regardless of A's setting. Somehow the call takes information with it saying in effect, "I am not really a call to B, I am a call to A only reaching B by virtue of forwarding, and how do we know A wants to really wind up with C ?".... The other generic operating here will chain-forward some absolute maximum number of times: this can be straight forward, A to B to C to D, or it can be in a circle, A to B to A to B to A, and at some point when it sees it is getting nowhere and is unable to ditch the call someplace then it quits and returns re-order to the original caller. PT]
John Higdon <john@bovine.ati.com> (12/30/89)
Miguel_Cruz@um.cc.umich.edu writes: > My phone number (313-663), certifiably a residence, allows seemingly infinite > concurrent call forwards with the regular Michigan Bell call forwarding > service. A little digging reveals that it is not a business/residence matter at all. It is simply a matter of feature implementation in the various switches/generic software releases. When the feature was first generally offered, it allowed unlimited unconditional forwards. When it was found that two numbers forwarded to each other could wipe out the entire trunk bank between the two switches, the generic was modified to allow only one forward. Later, it was realized that simply requiring each call to be supervised before the next was forwarded would prevent a trunk-gobbling loop and this change was folded into the 1AESS generic. My office CO has a 1AESS running the very latest generic (CLASS capable, I'm told) and can multiple forward, while my residence is "served" by an old rusty 1ESS running shareware (I'm told it's actually capable of connecting two telephones together, sometimes) and forwards exactly one call, period. > hear endless clicks as the call gets bounced back and forth, eating > up more and more trunks (or whatever they use for interoffice calls > these days..). If you can actually do this, it indicates that they are running a positively *ancient* generic and deserve to have all of their trunks disabled by pranksters, which I'm surprised hasn't happened already. If that were possible here, the trunks would be gone in an instant because of the SS#7 signaling employed. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@bovine.ati.com | San Jose, CA 95150 | M o o !
brian@ucsd.edu (Brian Kantor) (01/01/90)
Our campus Ericsson MD110 &*^$^%#%^ switch currently allows exactly one forward; when it was first installed you couldn't forward to a phone that was forwarded to you, but you could make a three-number loop and then crash the switch by calling any of the three numbers (complete crash: no audio paths, no ringing, no dial tone, DEAD!). Now you can set up a such a loop but the call will only forward once, and the switch won't crash. Actually, since they use divert-on-no-answer to provide voice mail, that means that I can't use my secretary's voice mail to answer my line, since even if I forward my phone to her number, it won't divert a second time to the voice mail. - Brian