Answer (and Disconnect) Supervision is needed whenever you are connecting the P32mxi to analog POTS circuits on a Central Office. One pitfall of using POTS circuits is that there is no way to tell when the called party on the local CO has answered. There is no signaling sent from the CO to the phone to let you know that the called party has answered. If you are using a DID (reverse battery) circuit instead of a POTS line, you do not need to use either the timer or VAD since the DID circuit provides both answer and disconnect supervision.
The Answer Supervision Feature of the P32mxi supports Answer Supervision for Network billing. There are two types of Answer Supervision: Timer-based (standard) or Voice Activity Detection (VAD)-based (which requires both the MX310 VX Board and the MX420 VAD Software package).
With the VAD-based Answer Supervision, (busy) signaling will be sent towards the calling party (the network) whenever the called party begins speaking. With the Answer Supervision Timer, busy signaling will be sent towards the network when the timer expires.
Included with the VAD software is Disconnect Supervision. Disconnect Supervision listens for a specific "disconnect" tone from the CO and then sends idle signalling towards the calling party. You cannot have timer-based disconnect supervision since you cannot determine how long a call is active for (some people talk for hours!).
This type of Answer Supervision is very basic. Once the FXO circuit is taken off-hook (via signaling from the T1/E1), an adjustable timer is started that will send "answer" signaling towards the network. To enable timer-based Answer Supervision, go to the Maintenance Menu, select Call Supervision, then select Timer Answer Supervision....
This value is the length of time to delay before sending "answer" towards the network. Typical values are from 12 to 15 seconds. A value of zero (0) turns the timer off.
Another way to access the Timer-Based Answer Supervision is through Register 13 (via the Maintenance Menu, Registers...). Note that this register may be labeled "Call Completion Timer" or "Answer Supervision Acknowledgement Time" depending on the version of software you have.
An optional hardware/software feature for the P32mxi, Voice Activity Detection-based Answer Supervision (VAD) is more accurate than the timer-based version since it actually listens to the call to determine when the called party has answered the phone. Once a conversation has started (or, a modem or fax call is detected), the system sends "answer" back towards the network.
To make the VAD Answer Supervision more accurate, the system needs to have certain tones and their frequencies defined. These tones will be ignored while the system is doing voice detection. Go to the Maintenance Menu, select Call Supervision, then select VAD Answer Supervision... to bring up the tone definition window:
The tones for over 180 countries have been defined and are accessed through the Country pull-down menu. Select your country and push the Use button to fill in all of the tones. If your county is not listed or if you know that your CO uses different frequencies for the audible supervision tones, you can manually enter the frequencies used by your CO. The "Extra Tone" is provided in case you need to ignore an additional frequency type.
In the Tone Configuration section, you need to specify that the tone is either Single Frequency (a pure tone), Dual Frequency, or an Amplitude Modulated tone.
For single frequency tones, set Frequency 1 to be the single tone frequency (in Hz), and Deviation is the deviation around that frequency (in Hz). Enter zero (0) for Frequency 2 and its Deviation. For dual frequency and amplitude modulated tones, set up both Frequency 1 and Frequency 2, and their frequency Deviation.
To skip to the next tone, press Next>> and repeat the process. When you have selected all of your tones, check the Enable Answer Supervision box, then press Finish.
The VAD software and the VX Board must be installed and the specific Feature Key entered for your system before the VAD Answer Supervision will work.
Included with the VAD-Based Answer Supervision is Tone-Based Disconnect Supervision. Once a call is established (i.e., Answer Supervision is sent towards the network), the system begins listening for Disconnect Supervision tones. When a Disconnect tone is detected, the system sends idle (or clear forward/backwards) signaling towards the network.
To make the Tone-Based Disconnect Supervision more accurate, the system needs to have the disconnect tones and their frequencies/cadences defined. Go to the Maintenance Menu, select Call Supervision, then select VAD Disconnect Supervision... to bring up the disconnect tone definition window:
There are two Disconnect Tones that can be programmed. Similar to the VAD Answer Supervision definitions above, you need to specify that the tone is either Single Frequency (a pure tone), Dual Frequency, or an Amplitude Modulated tone.
For single frequency tones, set Frequency 1 to be the single tone frequency (in Hz), and Deviation is the deviation around that frequency (in Hz). Enter zero (0) for Frequency 2 and its Deviation. For dual frequency and amplitude modulated tones, set up both Frequency 1 and Frequency 2, and their frequency Deviation.
The Cadence is used with tones that are not constant, such as the USA busy tone (1/2 second of tone, 1/2 second of quiet) and many others. In the USA busy tone example, there is only one cadence (on then off). This tone would be programmed to use the Period 1 cadence with the following timing:
Min On Time is the minimum time that the tone should be present (400 ms)
Max On Time is the maximum time that the tone should be present (600 ms)
Min Off Time is the minimum quiet time for the tone (400ms)
Max Off Time is the maximum quiet time for the tone (600ms)
Note that these frequencies and cadences are very country-specific and that you will have to know what frequencies and cadences your disconnect tones use. For a constant tone, the only required setting is the Min On Time (in Period 1) which determines how long it takes before the system declares the tone as present. Use zero (0) for any setting that is not used.
To skip to the next tone, press Next>> and repeat the process. When you have selected all of your tones, check the Enable Disconnect Supervision box, then press Finish.
The VAD software and the VX Board must be installed and the specific Feature Key entered for your system before the Tone-Based Disconnect Supervision will work.
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