Can you transfer key presses with Skype?

Discussion in 'UK VOIP' started by Roger Mills, Jul 16, 2013.

  1. Roger Mills

    Roger Mills Guest

    I currently only use free Skype from my laptop, to contact other Skype
    users, and have never bought any credit.

    I'm aware that I could also ring landlines or mobile phones belonging to
    non-Skype users, were I to buy some credit.

    I'm wondering whether I could then ring my home number while away from
    home, to access the messages on my answering machine. If I do this from
    a normal phone, I first have to press the star key to interrupt the
    outgoing message, and then enter some digits for a numerical password.

    Is it possible to do this from the computer running Skype, or can I only
    make pure voice calls? This would be useful in cases where I have WiFi
    access and would avoid having to make a potentially expensive
    (particularly if overseas) call using a mobile.
    Please reply to Newsgroup. Whilst email address is valid, it is seldom
    Roger Mills, Jul 16, 2013
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  2. Roger Mills

    Graham. Guest

    Skype as a system will pass inband DTMF to the far end fine, there is
    no reason to suppose this shouldn't be the case, unless a very
    bandwidth deficient CODEC was used, but as we know Skype audio is very
    All the Skype soft clients I have used are able to send DTMF once the
    call has been set up.

    My son made extensive use of a "3" Skypephone S2 while he was at Uni,
    as this allowed him to use Skype without any PAYG voice or data credit

    I set up a Skype to SIP gateway so he could make PSTN calls without
    going the (expensive) "Skype Out" route. It was essential that the S2
    generated inband DTMF tones for this to work, and I wasn't sure if
    they would be present. I was relieved to find that they were, and I
    can tell you my son gained, and the "3" network made no money at all
    from him.
    Graham., Jul 17, 2013
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  3. That seems very unlikely. Most VoIP systems, even those using G.711
    codecs, which are telephone toll quality 3.1kHz audio ones, decode DTMF
    and pass it as special control messages that are only converted back to
    DTMF at an ISDN or analogue system boundary.

    I would expect the Skype codecs to be vocoder type ones, e.g as used in
    all current mobile phones. Mobile phones do not transmit DTMF in band;
    it is generated by the base station based on special messages sent over
    the air interface. The comfort tone that you hear is not the one that
    is actually sent to the remote side.
    David Woolley, Jul 17, 2013
  4. Roger Mills

    Graham. Guest

    Thanks for that David, I just presumed it was inband.
    Graham., Jul 18, 2013
  5. Roger Mills

    Roger Mills Guest

    But now I'm a little confused as to whether or not what I want to
    achieve will work. Would Mr Woolley care to comment? [It doesn't really
    matter to me what the exact mechanism is for passing key presses - I
    just want to know whether or not Skype will do it!]

    P.S. I originally tried to post this a couple of days ago using a new
    version of Thunderbird and not realising that "Reply" now goes to an
    individual (subject to having a valid email address!) rather than to the NG.
    Please reply to Newsgroup. Whilst email address is valid, it is seldom
    Roger Mills, Jul 20, 2013
  6. I've never used SkypeIn or SkypeOut, but I would expect normal VoIP
    behaviour, i.e. that DTMF will be generated at the circuit switched
    network boundary, and probably that RFC 4833 (supercedes 2833) telephony
    events will be generated at a SIP boundary (which a SIP system would
    normally convert to DTMF tones at a circuit switched boundary).

    I would not expect tones from a tone box to work, only presses on the
    official digit keys.

    At least in other VoIP systems, it is possible for timing disturbances
    in the tones to mean it is possible to key sequences that are not
    reliably decoded.
    David Woolley, Jul 21, 2013
  7. Roger Mills

    Graham. Guest

    Just tried an acoustically coupled tone pad (my blackberry) and it
    works OK
    Dialled 0800 144 144 via Skype and managed to send 08 *3 with the BB
    to make the IVR speak French.
    Graham., Jul 21, 2013
  8. Roger Mills

    Roger Mills Guest

    I assume you meant *8 and 03 - but no matter.

    That works fine when I do it from a PC, and the IVR does indeed speak

    However, when I tried it from my Android tablet - which is what I would
    really like to use - it was a no-no. The numeric digits were ok -
    responding with a bleep when pressed - but there was no way that it
    would respond to the star and hash keys when pressed in-call (although
    it looked like they would have worked as part of the dialled number).

    Please reply to Newsgroup. Whilst email address is valid, it is seldom
    Roger Mills, Jul 21, 2013
  9. Roger Mills

    Roger Mills Guest

    Yes, all the digits - including zero - work both when setting up a call
    and in-call. Star and hash both work when setting up a call but *not*
    Please reply to Newsgroup. Whilst email address is valid, it is seldom
    Roger Mills, Jul 22, 2013
  10. Roger Mills

    Graham. Guest

    There used to be a lot of BT payphones that were perfectly capable of
    dialling DTMF whilst in a call, but not * and # because the buttons
    were simply not there.
    Graham., Jul 23, 2013
  11. Roger Mills

    Roger Mills Guest

    In my case, the (on-screen) buttons are there but they don't bleep when
    you press them in-call, and they obviously don't get transmitted because
    they don't produce the desired response.
    Please reply to Newsgroup. Whilst email address is valid, it is seldom
    Roger Mills, Jul 23, 2013
  12. Roger Mills

    Graham. Guest

    I would still be inclined to confirm that beyond doubt by calling
    another phone and listening for the tones as the called party. The
    "bug" might just be generating local confidence tones.
    Graham., Jul 23, 2013
  13. Roger Mills

    Roger Mills Guest

    I'm not quite sure what that would achieve. I can't call to a number
    which I own without having some Skype credit.

    I did the same test as you, by dialling 0800 144 144 and then pressing
    *8 and 03 to select different language/French

    When I did it from Skype running on my PC it worked fine. When I did the
    same thing on my Android tablet, it didn't. The fact that it didn't
    recognise the * key was terminal. Whether or not it received the numeric
    keys doesn't really matter - because without the * I can't do anything!

    It has at least avoided the need to buy Skype credit in order to test
    whether I can access my answering machine using he Android tablet.
    Please reply to Newsgroup. Whilst email address is valid, it is seldom
    Roger Mills, Jul 23, 2013
  14. Roger Mills

    Graham. Guest

    Actually I could call my own phone using that very 0800 number because
    I have an account number and PIN for the BT Chargecard service.

    I have had it for over 20 years, lost the actual card years ago but
    the 17 digits were long ago committed to memory. Not that I use it
    Graham., Jul 23, 2013
  15. I'm not sure what you have to press - my Skype client for Windows does not
    have a keypad, or maybe I just haven't found it. However I have a Binatone
    USB handset with a keypad and so I made your test by placing a call to the
    Skype Echo / Sound Test Service (Skype name echo123) and listened to the
    playback of those key presses and all 12 pressed buttons played back fine.
    Anthony R. Gold, Jul 24, 2013
  16. Roger Mills

    Graham. Guest

    That's my birthright, on account next month is the 60th anniversary of
    my birth.
    Graham., Jul 24, 2013
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