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This chapter describes how to configure a VFC-01 Expansion Module. These parameters define the operational characteristics of a VFC-01 expansion module. In the parameter descriptions that follow, some parameters can have different values based on the telephony interface type (FXO, FXS, or E&M). This interface type is selected by a switch on the physical VFC-01. In all parameter descriptions, references to the "local unit" refers to the unit being configured (LOCAL NODE or REMOTE NODE).
The configuration of voice cards let you specify the input and output voice levels and examine the resulting voice quality. The voice level settings affect the quality of audio that telephone users will hear during the normal operation of the FastPAD. Once you verify that all circuits are functioning properly and optimal voice quality is achieved, use the Configuration Worksheets in Appendix C to record the final configuration.
When the Expansion Channel option is selected from the Configuration Menu, the first expansion channel configuration screen is displayed in the following format:
Ex <n> VFC-01
Rate: 16K
DTMF Detect: YES
Interface: LOOP
This parameter specifies the expansion channel being configured where: <n> = the expansion channel number (1-8).
When the user dials a number, this parameter is passed across as part of a Call Setup frame. The voice call is established if there is enough bandwidth at the called and calling. FastPADs to allow for the minimum of the Rate configured for the connecting channels. It can be set to a value in the range 8 to 16 kbps. The default value is 16 kbps.
This parameter enables (ON), disables (OFF), for the regeneration of DTMF tones or specifies a number of seconds (2-255) in which DTMF tones will be regenerated. When enabled (ON), the FastPAD detects and regenerates DTMF tones. When disabled (OFF), DTMF tones are passed transparently to the remote unit
When a value in the range 2 to 255 is specified, the FastPAD will regenerate DTMF tones for the configured number of seconds. The default value is 30 (regenerate DTMF tones for 30 seconds including call setup).
This parameter specifies the telephony interface that will be used by this channel. It can be set to one of: Loop Start, 4-Wire E&M, 2-Wire E&M. Loop Start is the normal setting for FXS and FXO operating modes. It provides characteristics similar to those of a standard telephone or central office telephone circuit.
The 4-Wire E&M selection is the normal setting for a PBX E&M tie line interface that uses one pair of wires for the incoming voice signal and another pair of wires for the outgoing voice signal.
The 2-Wire E&M selection is for an E&M tie line that uses a single pair of wires for both the incoming and outgoing voice signal. The default value is Loop Start.
When you exit the Interface field, the next expansion channel configuration screen is displayed in the following format:
Ex <n> VFC-01
Suppression: **
In: 0db
Out: 0db
This parameter is used to specify the silence suppression level. The silence suppression level is specified by entering 1, 2, 3, 4, or 5 asterisks (*).
A larger silence suppression level results in greater savings in composite bandwidth. This allows more data channels to operate simultaneously with voice channels. The default value is two asterisks (**).
This parameter specifies the local voice level into the voice port, measured in 1 dB increments. The value of this parameter adjusts the sensitivity of the local voice channel to the signal from the attached device. The purpose of this parameter is to match the voice channel dB level to the input signal.
A more negative setting produces a higher input gain (i.e., +6 produces the least input gain, -31 produces the highest input gain). If the In level is reduced (made more negative), the voice channel will be more sensitive to the input; this will also cause the voice output at the Remote to sound louder. The default value is -9 dB for FXS operating mode, -13 dB for FXO, and -15 dB for E&M.
This parameter defines the output level of the local voice port. It can be set to a value in the range +6 to -31 dB. A more positive setting produces a higher volume (i.e., +6 produces the highest volume, -31 produces the lowest volume). The default value is -13 dB for FXS operating mode, -9 dB for FXO, and -15 dB for E&M.
If a call is active and voice traffic is present on the selected channel, asterisk characters (*) are displayed next to your entry as In and Out levels are specified. These asterisks indicate the actual voice levels into and out of the FastPAD as voice input and output levels are being specified. Typically, between 3 and 4 asterisks (*** or ****) will be displayed when the setting is optimal.
Actual operating levels may vary considerably, depending on the type of voice circuit and connection interfacing the voice channel, the type and quality of telephone instruments used, and the speakers. Start with the default values shown, and adjust each level 1 or 2 dBs in either direction until the optimum voice quality is achieved.
The VFC-01 module is capable of operating as an FXS, FXO, or E&M device and each device type has its own unique requirements for voice levels that will provide the highest quality voice. The perceived voice quality is also affected by the type of telephone handset being used, ambient noise conditions, and the characteristics of the speaker's voice.
Because so many variables affect voice quality, it is usually necessary to fine tune the voice levels beyond the recommended settings. For example, the recommended settings for FXS are -9 dB input and -13 dB output. The adjustment of input level determines the sensitivity of the voice channel to the incoming signal. With a default setting of -9 dB, the voice channel expects a -9 dB input signal. If the actual input signal is -20 dB, it will be too weak and the resulting output at the remote will also be weak. Therefore, the input level setting must match the dB level of the actual incoming signal.
The output level is similar to a volume control and should be set to match the level expected by the attached device. A proper adjustment should provide a comfortable listening level with no distortion or overdriving of the signal.
The following steps describe how to adjust voice levels settings and the local and remote sites.
Step 2 From the Configure menu, select the expansion channel number where you want to set voice levels.
Step 3 Use the <Down Arrow> key to select the configuration screen where In and Out levels are set in this screen:
Ex <n> VFC-01
Suppression: *
In: -9 dB ****
Out: -13 dB ****
Step 4 Set the Input level to -9 dB for an FXS connection, -13 dB for an FXO connection, or -15 dB for an E&M type connection.
Step 5 While speaking into the handset in a normal voice, observe the level indicators adjacent to the In field. The display should indicate an average of between three and four asterisks (*) next to the "In" caption at the bottom of the window.
Step 6 If the display shows more than four asterisks, it means the actual signal is stronger than the voice input level setting. When this is the case, reconfigure the channel to a less sensitive setting or to a higher (less negative) number (e.g., -7 dB for an FXS connection).
Step 7 If the voice sounds weak with missing syllables or the display shows less than three asterisks, it means the incoming signal is weaker than the configured setting. When this is the case, adjust the input level to a higher sensitivity setting—which means a lower (more negative) level (e.g., -11 dB for an FXS connection).
Step 8 Continue adjusting the level higher and lower in two dB increments, then one dB increments until the In level displays three and one-half asterisks.
Step 9 Instruct the person at the remote site to complete steps 1-8 for the input level (their local input level) at the remote unit.
When input levels have been adjusted to the appropriate values at both the local and remote sites, this procedure can be repeated for local and remote output levels. The starting output level values are -13 dB for FXS, -9 dB for FXO, and -15 dB for E&M.
When adjusting the local output level, instruct the person at the remote site to speak in a normal voice while you observe the local Output level indicator. Between three and four asterisks should be displayed next to the Out caption when the voice is at a comfortable listening volume with no overdriving of the volume.
If necessary, adjust the local output level until three and one-half asterisks are displayed. Repeat the output adjustment for the remote unit by speaking in a normal voice as the remote person adjusts the remote output level (their local output level).
The new level settings take effect when saved to Active or Active and Saved in the Store To menu.
When you exit the Out field, the next expansion channel configuration screen is displayed:
Ex <n> VFC-01
Call Timer: 5
In Hunt Group: A
Long Dial Prefix: #
This parameter specifies the amount of time the FastPAD should wait for a response to a Call Connect or Call Clear request. It can be set to a value in the range 1-30 seconds. The default value is 5 seconds.
When the FastPAD issues a Call Connector or Call Clear request, it will set a timer equal to the value specified here. If that timer expires with no response from the destination, the FastPAD will generate a busy tone.
This parameter includes the channel in Hunt Group A or B, or excludes the channel from an Expansion Channel Hunt Group. The default value is A.
(A) indicates this channel belongs to Hunt Group A. (B) indicates this channel belongs to Hunt Group B. (No) excludes the channel from both hunt groups.
This parameter is used to specify a prefix character that is required preceding calls using the long call format. It can be set to a single digit 0-9, asterisk (*), or pound-sign (#). The default value is the pound sign (#).
When the user at an attached device (e.g., telephone or Fax machine) dials a long form number (i.e., not a speed dial number), it must be preceded by the prefix character specified in this field.
When you exit the Long Call Prefix field, the next expansion channel configuration screen is displayed:
EX <n> <VFC-01>
Auto Dial: NO
Call Retry Timer: 5
This parameter enables (YES) or disables (No) the auto dial function. When this parameter is enabled (YES), the Number field will be added to the configuration screen. When enabled and the handset attached to this port is taken off-hook, the system will attempt to establish a connection to the configured Number. The default value is NO (disabled).
If the Auto Dial parameter is set to YES, one or more auto dial number fields will be added to this screen.
For a VFC-01 module type, you may specify a Fax number:
EX <n> <VFC-01>
Auto Dial: YES
FAX <xxx>
In the FAX field, enter a speed dial number that is defined in the Map configuration table. The number of digits (2, 3, or 4) that can be entered is limited to the number of Dial Digits specified in System Configuration. The system will automatically dial the long-form number defined in Map configuration that is associated with speed dial number that you specify in this field.
The next expansion channel configuration screen is displayed:
EX <n> <VFC-01>
FXOI Timeout: 30
The Local FXO timeout parameter defines the amount of time (1-99 seconds) that the local port connected to the PSTN will wait before an actual Fax transmission begin. If there is no Fax tone when this timer expires, the connection will be terminated. The default value is 30 seconds.
This is the last configuration screen. You may use the <Up Arrow> and <Down Arrow> keys to review your entries.
Press the <Enter> key to display the Store To screen described below.
Store to:
ACTIVE & SAVED
ACTIVE ONLY
SAVED ONLY
This selection will store the configuration parameters in EEPROM and use them immediately.
This selection will allow you to use the new configuration parameters immediately, but they will not be stored permanently. The changes are stored in RAM but not in non-volatile EEPROM.
This selection will store the configuration parameters in EEPROM, but they will not be used until the next power-on reset or cold boot start.
You may also press the <Esc> key in this or any other configuration screen to exit the configuration function without changing anything.
When you press the <Enter> key in the Store To menu, the system will confirm your selection with a screen in the following format:
Saving Configuration
Posted: Thu Jan 25 13:32:11 PST 2001
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