Inter-Tel AXXESS Manual page 1096

Programming
® ®
INTER-TEL AXXESS
Method B
1.
2.
3.
4.347 Run a Hybrid Balance Test: The Hybrid Balance Test provides data that allows you to
optimize the Hybrid Balance Setting on loop/ground start trunk ports connected to loop/ground
start trunks.
4.348 The Hybrid Balance Test generates 20 measurements of Echo Return Loss (ERL) at the
trunk-port interface, one for each possible Hybrid Balance setting. By entering in DB Program-
ming the optimal Hybrid Balance setting for each trunk, you can minimize echo from the CO
interface into the system. And, if needed, you can provide actual ERL data in terms of dB loss
for each loop/group start trunk attached to the Axxess system.
•
•
•
Page 6-246
MANUAL VERSION 11.0 – May 2008
Right-click on the current CO Trunk Group setting and select
. A window appears that asks you to select the type of device to include.
Group
Select CO Trunk Group and then select
view them in a list by selecting the List button or view details by selecting the Details
button.)
Highlight the desired trunk group and then select
Trunk Group field.
NOTE:
You can also move trunks between trunk groups as described on
Definitions: Echo Return Loss (ERL) refers to the difference between the transmitted
and reflected audio levels. The higher the ERL, the lower the level of echo. The term
"hybrid balance" describes the relationship of the impedances of the local loop start or
ground start trunks on the Axxess system. The Hybrid Balance Setting for a trunk port
can be adjusted to achieve a better match of impedances.
Background: In general, echo occurs in IP audio because of inherent delays associated
with packet switching through a network. On the Axxess system, echo in IP audio is
associated with the increased use both of IP networking and of IP endpoints in the mar-
ketplace. Initially, the Hybrid Balance setting is programmed in accordance with a
region-specific default value. This default value, however, may not be optimum for all
loop/ground start trunks, and an adjustment to the Hybrid Balance setting is required.
The Hybrid Balance Test provides real-time data you can use to reprogram the Hybrid
Balance setting.Using data provided by the Hybrid Balance Test, you can minimize
echo on trunk interfaces by programming the Hybrid Balance setting to a recommended
optimal setting for each interface. As a result, any IP-based connection utilizing a trunk
may have noticeably reduced echo. For programming instructions, see
Source of Hybrid Balance Assessment Data: Assessment data for adjusting the
Hybrid Balance setting is generated from the Digital Signal Processor (DSP) Echo
Diagnostic and the Call Processing (CP) Hybrid Balance Diagnostic. The DSP Echo
Diagnostic feature provides a means for quantifying the level of echo present on a given
trunk. One function on the DSP plays a set of tones out on the transmit line of the trunk,
and a second function listens on the receiving line of the trunk to determine the level of
the reflected audio. The DSP performs this test for a specified duration and sends the
measurement result to CP. The CP Hybrid Balance Diagnostic feature makes requests of
the DSP Echo Diagnostic and searches the measurement results to determine the opti-
mal setting for each of the loop start trunks. CP reports all results and a test summary
using free-form Message Print.
. The list of trunk groups appears. (You can
Next
. Your selection appears in the
Finish
Change CO Trunk
page 6-228.
page 6-247.
Trunks