Cisco SPA962-NA Administration Guide - Page 23

Chapter 1 Introducing Linksys 900 Series IP Phones Feature Descriptions Table 1-4 Linksys ATA Features (continued) Feature Voice Activity Detection with Silence Suppression and Comfort Noise Generation Configurable Dial Plan with Interdigit Timers Report Generation and Event Logging Syslog and Debug Server Records Dynamic Payload Call Statistics and Reporting Description Voice Activity Detection (VAD) with Silence Suppression is a means of increasing the number of calls supported by the network by reducing the required bidirectional bandwidth for a single call. VAD uses a very sophisticated algorithm to distinguish between speech and non-speech signals. Based on the current and past statistics, the VAD algorithm decides whether or not speech is present. If the VAD algorithm decides speech is not present, the silence suppression and comfort noise generation is activated. This is accomplished by removing and not transmitting the natural silence that occurs in normal two-way connection. The IP bandwidth is used only when someone is speaking. During the silent periods of a telephone call, additional bandwidth is available for other voice calls or data traffic because the silence packets are not being transmitted across the network. Comfort Noise Generation provides artificially-generated background white noise (sounds), designed to reassure callers that their calls are still connected during silent periods. If Comfort Noise Generation is not used, the caller may think the call has been disconnected because of the "dead silence" periods created by the VAD and Silence Suppression feature. SPA900 Series IP phones have three configurable interdigit timers: • Initial timeout (T)-Handset off hook; no digit pressed yet. • Long timeout (L)-One or more digits pressed, more digits needed to reach a valid number (as per the dial plan). • Short timeout (S)-Current dialed number is valid, but more digits would also lead to a valid number. SPA900 Series IP phones report a variety of status and error reports to assist service providers in diagnosing problems and evaluating the performance of their services. The information can be queried by an authorized agent, using HTTP with digested authentication, for instance. The information may be organized as an XML page or HTML page. SPA900 Series IP phones support detailed logging of all activities for further debugging. The debug information may be sent to a configured Syslog server. SPA900 Series IP phones provide configuration settings that determine the type of activity/events that should be logged, as for instance, a debug level setting. When no static payload value is assigned per RFC 1890, SPA900 Series IP phones can support dynamic payloads for G.726. The statistics collected by SPA900 Series IP phones during normal operation statistics are available in the Info tab. Line status is reported for each line (1 and 2). Each line maintains up to 2 calls: Call 1 and 2. Document Version 3.0 Linksys 900 Series IP Phone Administrator Guide 1-9