jjw7384@ultb.isc.rit.edu (Jeff Wasilko) (02/02/90)
I am trying to find out how call waiting will affect a MNP class 5 reliable connection. What I am trying to do is set up call forward-on-busy to my cellular number from my landline number (by manually forwarding calls to my cellular number before making a data call), so that when I am on the modem for extended periods of time I can still receive calls. After calling Rochester Telephone (lack of) Customer Service, I am told that call forwarding will only forward a call when the line rings. If the line is busy, the caller will receive a busy signal. Their solution is for me to get call waiting, so that the caller will not receive a busy signal. I am concerned that the call-waiting beep may drop my connection even though it is a reliable connection. Note: This is a better alternative for me than getting a second line installed since I work for Cellular One and get all my local airtime free :-). RochTel doesn't offer forward on busy or residential centrex, and hunting to a cellular number isn't possible. Note 2: Our rates in Rochester are probably the lowest in the country: $10/month, .175/min for peak periods. (-: (-: Jeff | RIT VAX/VMS Systems: | Jeff Wasilko | RIT Ultrix Systems: | |BITNET: jjw7384@ritvax+----------------------+INET:jjw7384@ultb.isc.rit.edu| |UUCP: {psuvax1, mcvax}!ritvax.bitnet!JJW7384 +___UUCP:jjw7384@ultb.UUCP____+ |INTERNET: jjw7384@isc.rit.edu |'claimer: No one cares. | [Moderator's Note: I *think* the rep led you astray. I have call forwarding on a line which does not have call waiting. When the line is free, a forwarded call is signaled with a single ring. When the line is busy, the call simply forwards. What the rep may have meant was only one call can forward at a time (true in some CO's). If the line is busy (becase a call is presently forwarded through it elsewhere), then subsequent calls will receive a busy. I think you should double check this yourself with a confederate and a second phone line. While the line is on forwarding and busy with an *outgoing* call, have the confederate dial it and see what happens, etc. I think the rep also led you astray telling you you had to have call waiting to make it work: how could you possibly have a phone forwarding and still get a call waiting signal at the same time? PT]
tronix@polari.UUCP (David Daniel) (02/03/90)
Just in case you DO need Call Waiting to set up your forward-on-busy
arrangement you need to do this:
Change the value of register S9 Carrier Detect Time from the default
of 7 (.7 seconds) to 15.
This increases the time between loss of carrier and modem disconnect.
Of course the host modem will need to be on an eqivalent setting as
well.
---- "What's so funny 'bout peace, love & understanding?"
Elvis Costello
[Moderator's Note: As you point out, the other end needs the same
change in its register. Its unlikely the typical user will have access
to the modems on the other end (terminal servers, BBS lines, email and
other commercial services), thus for all practical purposes, this
really won't make any difference. Also, depending on how important
your data is (or difficult to decipher/read if binary code, etc), you
will lose data and gain garbage in its place during that interim. PT]tronix@polari.UUCP (David Daniel) (02/04/90)
Our moderator's note as regards data loss and trash induced by Call
Waiting is valid. However any error-correcting protocol would simply
resend the effected block as the checksum would not vailidate.
"What's so funny 'bout peace, love & understanding?"
Elvis CostelloMiguel_Cruz@ub.cc.umich.edu (02/05/90)
In Digest 10.75, David Daniel said something to the effect that Call Waiting would not cause problems with protocol file transfers because the checksums would not match and the packet would simply be resent following the call waiting burst. The problem with this is that many modems, especially on long distance calls, simply drop carrier and hang up while the call waiting tone is obscuring the far-end carrier. Even if you set your modem to wait a long time before dropping carrier, there is no guarantee that the remote modem has been similarly adjusted. So, the protocol's ability to recover is largely a moot point, as the two modems will more likely that not have disconnected by the time the call waiting tone's over.
Vance Shipley <vances@xenitec.on.ca> (02/05/90)
In article <3473@accuvax.nwu.edu> tronix@.UUCP (David Daniel) writes: [discussion of call waiting on modem lines...] >Change the value of register S9 Carrier Detect Time from the default >of 7 (.7 seconds) to 15. >This increases the time between loss of carrier and modem disconnect. >Of course the host modem will need to be on an eqivalent setting as >well. Actually, most offices do not pass the call waiting indication tone to the far end. Some will blank out the tone (to prevent the wrong party from thinking they have a call waiting). In this case the far modem will need to be as forgiving ablout carrier loss. Others (mine) do not give any indication at all, the modem would continue to send carrier. In any case it would be dependent on your CO so it will work the same way for all calls. Vance Shipley SwitchView - Linton Technology vances@xenitec.UUCP [Moderator's Note: In a digital CO, the other end hears *nothing at all*. The only way you know the other person has a call waiting (as opposed to the click you hear while the other person hears tone in older systems) is if they are talking, you hear their voice drop out for a half second. If you are talking at that instant, you detect nothing. PT]
jgro@apldbio.com (Jeremy Grodberg) (02/07/90)
In my experience, the default MNP settings are good enough to keep the modem from hanging up when a call-waiting tone is recieved. The block of data being transmitted is trashed by the tone, but the error correction retransmits it and no data is lost. In fact, I had to go to pains to get my modem to hang up when it got the call waiting tone (so incoming calls would have priority over modem calls, unless I turned off call waiting). I used to live in Rochester, and I have had no shortage of incorrect information from RochTel. The are certainly the worst phone company I have worked with. Even their special services department, which is usually the sharpest group at the phone company, gave me bogus advice about ordering special event lines. So I would triple check thier assertion that call forwarding won't work if the phone is off the hook. Jeremy Grodberg jgro@apldbio.com "Beware: free advice is often overpriced!"