VoIP Hardware Echo Cancellation

Xorcom’s hardware echo cancellation module is an alternative to the OSLEC software echo cancellation solution typically used in Asterisk systems.

P/N = XR0124

Hardware Echo Cancellation Reduces Server CPU Load and Enhances Voice Quality
Hardware Echo Cancellation Module Increases Number of Simultaneous Calls Supported

Xorcom’s hardware echo cancellation module is an alternative to the OSLEC software echo cancellation solution typically used in Asterisk systems.

Xorcom has designed a hardware echo canceller (HWEC) module for its award-winning Astribank telephony interfaces and Asterisk-based IP-PBX appliances*. The module provides a high level of echo cancellation and voice enhancement while reducing the load on the CPU, as compared to OSLEC, the software-based echo cancellation solution provided in the standard Asterisk framework.

Comparison Between Software and Hardware Echo Cancellation

Prior to the development of the hardware echo cancellation module, Xorcom recommended that customers use the OSLEC (Open Source Line Echo Canceller) provided as part of the Asterisk operating system. Central Processing Units (CPUs) are so powerful these days that normally the OSLEC has no impact on the IP-PBX operation. However, if the telephony system is used in high-density call environments, and/or where additional applications are involved, such as call centers that need call recording functionality, offloading the echo cancellation processing to a separate hardware module makes sense.

Load Test Results Tell the Story

By reducing the load on the server’s CPU, the number of simultaneous calls that are supported on the telephony system is increased significantly. The echo tail size of the hardware echo cancellation module has been set to 128 taps, and load tests show that the same number of simultaneous calls is achieved as when the software echo cancellation is disabled completely.

Ordering the Hardware Echo Cancellation Option

Each separate Astribank or Xorcom IP-PBX** requires a single Echo Canceller card. The hardware echo canceller option includes 32 voice channels and support for up to a total of 144 channels. All ports/channels in the chassis need to be licensed for the module to function. Additional channels are licensed in bundles based on the telephony interface type:

Additional PRI Port
P/N LC0020: License(s) necessary for 2nd, 3rd, 4th activated PRI port(s) in the chassis
Additional FXS Module
P/N LC0021: License support additional FXS module(s) in PRI or BRI configuration. Note: Hardware Echo Cancellation cannot be applied to FXO modules in a single chassis configuration including a PRI or BRI module. In this case, the FXO module should be installed in a separate (Astribank) chassis
Additional BRI Channels
P/N LC0022: License(s) support(s) up to 16 voice channels, in two-channel bundles

Hardware Echo Cancellation Limitations and Configuration Tips

Before you configure a system that includes the Xorcom hardware-based echo cancellation (HWEC) module you should be aware of a few design limitations:

HWEC is not supported in the C/XR1000 or CXS1000 models.
For certain telephony module combinations, not all port types will be able to use the HWEC.

* Except for the low-end C/XR1000 and CXS1000 “Spark”, which do not support the hardware echo cancellation module.
** The echo cancellation hardware is an integral part of the Astribank devices with 6 or more PRI ports and does not need to be ordered separately.