CLI Procedure for PBX Station/CENTREX PSTN Line App. Adjustments

For this procedure, one voice channel with an FXS interface is required as a companion channel. If there are no other voice channels available locally, then the local FXO voice channel will have to be connected to a companion FXS voice channel across the network. In that case, two technicians will be required to perform the adjustment procedure, one at each end. If no FXS channels are available in the network, one will have to be temporarily configured or installed.

Note: If there are no single-line telephone circuits available from the PBX or CENTREX/PSTN, then the line assigned to the channel that is temporarily converted to FXS can be used for test purposes.

1. Use the test setup shown in the figure below. Initially, set both Voice Network Analyzers to BRDG, TEST, and OFF. The PBX station numbers and network extension numbers in the following figure are fictitious, used here for reference only.



2. Place a call from PBX station 123 to station 456. To do that, lift the No. 1 telephone off-hook, wait for the dial tone from the PBX, then dial number 456. You should hear the dial tone from voice channel number 1. Dial extension number 16. The No. 2 telephone set will ring.
3. Place the SETUP switch on the No. 2 Voice Network Analyzer to TERM. The telephone will stop ringing.
4. Place the SETUP switch on the No. 1 Voice Network Analyzer to TONE, and disconnect the No. 1 telephone from the Voice Network Analyzer.
5. From the Command Line Interface, display the voice status as in step 8 of the CLI Procedure for Adjusting E&M Voice Channels.
6. Observe the display on the asynchronous terminal (use the CLI> show voice channel status command) and note the input level for the channel. If the reading is more positive than -4 dBm, apply attenuation (negative gain) in the amount that this reading is above -4 dBm. If the reading is more negative than -4 dBm, add gain (6 dB maximum) until the reading is below -4 dBm. Normally, station circuits require an Input Level Gain setting of between +2 and +4 dB in order to obtain the -4 dBm reading. In most cases, you will not have to use a negative Input Level Gain setting (-1 dB or lower). CENTREX or PSTN lines normally require an Input Level Gain setting of +2 to +6 dB.

To adjust the input level for the FXO channel, set the Input Level Gain for the appropriate voice channel.

To do that, you must first find the profile ID number associated with that channel, then change the input level setting of that profile. To find the profile ID number, enter:

CLI> show voice parameters table

You will receive the following typical display for both E&M voice channels:

7. Note and write down the Profile ID number. In the above example, both channels 1 and 2 are assumed to be in logical interface module b (limb), and the profile ID is assumed to be 3. Next, access the CLI>set voice profile inputLevelGain menu, use 3 for the Profile integer, then add or subtract gain as necessary by changing the InputLevelGain integer. Finally, update the configuration using the CLI>save configuration command.
8. After the input level gain adjustment is completed, write down the setting used to bring the input level to -4 dBm. You will need it for setting other FXO channels.
9. You have now established the input level gain setting on the FXO voice channel. In the following steps you will adjust the output level attenuation setting on the FXO channel.
10. Reconnect the No.1 telephone set to its Voice Network Analyzer.
11. Set the SETUP switch on both Voice Network Analyzers to BRDG.
12. Take the No.2 telephone set off-hook. You will receive a dial tone from voice channel number 2. Dial extension 15. You will receive a dial tone from the PBX. Dial station 123 (or PSTN telephone number). The No.1 telephone set will ring.
13. Place the SETUP switch on the No.1 Voice Network Analyzer to TERM. The telephone will stop ringing.
14. Place the SETUP switch on the No.2 Voice Network Analyzer to TONE, and disconnect the No.2 telephone from the Voice Network Analyzer.
15. Display the input level status of voice channel 2 (FXS). If other than
    -4 dBm, make the necessary adjustments. To do that, follow the procedure of step 6.
16. Read the value of the receive level on the No. 1 Voice Network Analyzer display. The receive level should be -12 dBm or lower. If the reading is more positive than -12 dBm, adjust accordingly, record the setting, then save. Use the recorded value for setting other FXO voice channels.
17. Now that both channels are adjusted, test the voice quality. To do that, place both Voice Network Analyzer SETUP switches to BRDG, take the No. 2 telephone off-hook, dial 15, wait for the dial tone and dial station 123. Talk to verify that there are no echoes. If there are echoes, the output level attenuation of the No.1 channel is too low. You must increase the output attenuation setting of the FXO channel.
18. Restore the FXS voice channel to FXO; it was used temporarily as a companion device with the FXO voice channel under test. Restore all channels to system controlled Busy.

End Of Topic