Generation and usage of inband tones on ISDN lines by SwyxWare (kb2368)

The information in this article applies to:

  • SwyxWare from version 3.20
  • HST SAPHIR V Primary PCI
  • Digi DataFire Quad Micro
  • Digi DataFire Micro V

[ Question | Answer ]


Which tones will be received from or generated to ISDN line by SwyxWare?


During a phone call you will hear different tones and announcements depending on call state:

  • After hook-off you get a strait tone - called Dial tone - if connected strait to PSTN. In case of connected to a PBX you usually get a sequence of three short tones with a longer pause (internal Dial tone).
  • After dialing the first digit the tone will be switched off. If connected to a PBX you will hear the PSTN dial tone after dialing the public line access code.
  • After dialing your destinations number you will hear the Alert tone. This is a sequence of a long tone witl long pause or two short tones with a long pause in UK.
  • In the case your destination is busy you will hear the Busy tone which is a sequence of shorter tones.
  • If no line is available to place your call, e.g. if both channels of a ISDN basic rate connection are already occupied by other calls, you will hear the Congestion tone. This is a sequence of very short tones.
  • If dialing a number which can't be resolved you will hear a Special information tone. This is a sequence of three short tones with increasing frequency.
  • In case the called party hooks on your may hear the Busy tone.
  • There are more announcements which may be heard in special situations. Most likely you will get an announcement like "The number has changed. Please dial...".

The different tones and announcements will always be generated by the network side of the ISDN connection. The presence of tones or announcements within the speech channel will be indicated in the call-signaling channel.

Overview to different scenarios:

  • SwyxWare is connected directly to PSTN:
    The tones and announcements will be generated by the PSTN switch. If the presence of tones or announcements is indicated to the SwyxGate by the switching equipment these tones will be forwarded to the SwyxWare terminal endpoints (SwyxIt!, L420 etc.). Otherwise the terminal endpoints will generate the tones locally depending on the call state.
  • SwyxWare is connected to already present PBX system:
    Same situation as described above. Important fact: if the PBX systems indicated presence of tones or announcements, these tones must really present in the speech channel. Otherwise the generation of local tones would be switched off by the SwyxWare terminal endpoints and the user wouldn't hear anything!
  • PBX or ISDN terminal endpoint connected to SwyxWare:
    In this case the SwyxGate will generate all appropriate tones depending on the call state. This will be indicated in the call-signaling channel. Therefore the user experience is similar like connected directly to the PSTN.



Comment on this article

If we have any follow-up questions, where can we contact you?

E-Mail Address (optional)


This feedback form can't be used for support requests. Those requests must be directed to your Swyx reseller or distributor.