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modem to phone pickup — Parallax Forums

modem to phone pickup

ArchiverArchiver Posts: 46,084
edited 2004-04-26 20:09 in General Discussion
Hi

I have a stamp hooked up to a modem, successfully making and receiving
calls. What I would like to know is if anyone has an idea how to get
the stamp / modem to detect when the remote phone has answered a call.

This is not modem to modem communication, it is modem to telephone.

Any help much appreciated.

James

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2004-04-24 19:55
    I used to do telephone work a long time ago and the telephone line switched
    polarity when the distant part swered. Normally, "Tip" is positive and
    "Ring" is negative and when the call is answered, "Tip" becomes negative and
    "Ring" becomes positive. I haven't done this type of work for over twenty
    years so this info might be bogus now - you can check it with a meter. Good
    luck....
    Bob


    Original Message
    From: jes_coupe [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=ow-MF2WuVTp9FHTfEReO1bcsqHO9X-MHuMPXyx57-loF-FdYzQI3LQOP_GpaozhUNQQMNFrHyJ9uKPx7]jes_coupe@y...[/url
    Sent: Saturday, April 24, 2004 11:11 AM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] modem to phone pickup


    Hi

    I have a stamp hooked up to a modem, successfully making and receiving
    calls. What I would like to know is if anyone has an idea how to get
    the stamp / modem to detect when the remote phone has answered a call.

    This is not modem to modem communication, it is modem to telephone.

    Any help much appreciated.

    James





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  • ArchiverArchiver Posts: 46,084
    edited 2004-04-25 00:22
    Thanks for the suggestion: in my test, the line goes high when the
    modem dials, but nothing changes on the meter when the call gets
    answered. So I guess there must be another solution?

    --- In basicstamps@yahoogroups.com, "okay_2" <okay_2@c...> wrote:
    > I used to do telephone work a long time ago and the telephone line
    switched
    > polarity when the distant part swered. Normally, "Tip" is positive and
    > "Ring" is negative and when the call is answered, "Tip" becomes
    negative and
    > "Ring" becomes positive. I haven't done this type of work for over
    twenty
    > years so this info might be bogus now - you can check it with a
    meter. Good
    > luck....
    > Bob
    >
    >
    >
    Original Message
    > From: jes_coupe [noparse][[/noparse]mailto:jes_coupe@y...]
    > Sent: Saturday, April 24, 2004 11:11 AM
    > To: basicstamps@yahoogroups.com
    > Subject: [noparse][[/noparse]basicstamps] modem to phone pickup
    >
    >
    > Hi
    >
    > I have a stamp hooked up to a modem, successfully making and receiving
    > calls. What I would like to know is if anyone has an idea how to get
    > the stamp / modem to detect when the remote phone has answered a call.
    >
    > This is not modem to modem communication, it is modem to telephone.
    >
    > Any help much appreciated.
    >
    > James
    >
    >
    >
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the
    Subject and
    > Body of the message will be ignored.
    >
    > Yahoo! Groups Links
  • ArchiverArchiver Posts: 46,084
    edited 2004-04-25 01:09
    This info. may be a bit dated... I have not worked in telephony for ~ 10
    years or so... but I don't think the basics have changed....

    I think what you are looking for is "answer supervision". In the context of
    telephony (in North America), the answering of the call is detected by the
    terminating end office, it is then passed through the network down to the
    originating office. In the case of a standard line to line call, the
    answering at the terminating end is detected by the absence or existence of
    current on the loop, this depends if the line is ground or loop start. This
    answer is propagated back to the originating office by various means
    depending on the equipment between. This is what tells the originating
    office to stop audible ringback to the originating phone and connect a two
    way network path between the two parties.

    Regardless, the answer supervision is typically not passed back to the
    originating line since in most cases it is not needed. It is typically only
    passed back if you have a "PBX" business line.

    Most automatic dialing telephone systems, used by telemarketers, use tone
    detection to determine when the line has been answered. The sequence is
    usually...

    - look for dial tone
    - break dial tone
    - dial the number
    - look for ringback tone (ringing 20 IPM) as opposed to busy tone (60 IPM)
    or re-order tone (120 IPM)
    - look for loss of ringback tone (maybe answered)
    - look for voice on the line (maybe answered, someone talking, but could be
    an announcement)

    If you do a search on google for "automatic dialer" you will find all kinds
    of information. I think that I remember playing with some modems that
    would actually give you indication that the call has been answered or you
    were getting busy tone etc...

    I hope this helps a little.

    Original Message
    From: "jes_coupe" <jes_coupe@y...>
    To: <basicstamps@yahoogroups.com>
    Sent: Saturday, April 24, 2004 7:22 PM
    Subject: [noparse][[/noparse]basicstamps] Re: modem to phone pickup


    > Thanks for the suggestion: in my test, the line goes high when the
    > modem dials, but nothing changes on the meter when the call gets
    > answered. So I guess there must be another solution?
    >
    > --- In basicstamps@yahoogroups.com, "okay_2" <okay_2@c...> wrote:
    > > I used to do telephone work a long time ago and the telephone line
    > switched
    > > polarity when the distant part swered. Normally, "Tip" is positive and
    > > "Ring" is negative and when the call is answered, "Tip" becomes
    > negative and
    > > "Ring" becomes positive. I haven't done this type of work for over
    > twenty
    > > years so this info might be bogus now - you can check it with a
    > meter. Good
    > > luck....
    > > Bob
    > >
    > >
    > >
    Original Message
    > > From: jes_coupe [noparse][[/noparse]mailto:jes_coupe@y...]
    > > Sent: Saturday, April 24, 2004 11:11 AM
    > > To: basicstamps@yahoogroups.com
    > > Subject: [noparse][[/noparse]basicstamps] modem to phone pickup
    > >
    > >
    > > Hi
    > >
    > > I have a stamp hooked up to a modem, successfully making and receiving
    > > calls. What I would like to know is if anyone has an idea how to get
    > > the stamp / modem to detect when the remote phone has answered a call.
    > >
    > > This is not modem to modem communication, it is modem to telephone.
    > >
    > > Any help much appreciated.
    > >
    > > James
    > >
    > >
    > >
    > >
    > >
    > > To UNSUBSCRIBE, just send mail to:
    > > basicstamps-unsubscribe@yahoogroups.com
    > > from the same email address that you subscribed. Text in the
    > Subject and
    > > Body of the message will be ignored.
    > >
    > > Yahoo! Groups Links
    >
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@yahoogroups.com
    > from the same email address that you subscribed. Text in the Subject and
    Body of the message will be ignored.
    >
    > Yahoo! Groups Links
    >
    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2004-04-26 20:09
    On Sat, 24 Apr 2004, Denis Thibault wrote:

    > Most automatic dialing telephone systems, used by telemarketers, use tone
    > detection to determine when the line has been answered. The sequence is
    > usually...

    Actually most automatic dialing systems use T1's for dialtones, which have
    more sophisticated mechanisms for doing signalling. In the case of ISDN
    PRI, which is quite common, it's literally a digital control message that
    tells the failure condition, much like any other data protocol.

    Sean T. Lamont, Chief Mad Scientist |-- lamont@a...
    Zen Chemical Productions |-- http://www.zenchemical.com
    Fabricators of Unnecessary Amazement
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