Linksys RTP300 User Guide - Page 48

Configuring Voice Services Silence Suppression and Comfort Noise Generation (e)). This is available only for FSK-based CID methods: (Bellcore, ETSI FSK, and ETSI FSK With PR). • Off Hook Caller ID - This is used to delivery caller-id on incoming calls when the attached phone is off hook (see the following figure). This can be call waiting caller ID (CIDCW) or to notify the user that the far end party identity has changed or updated (such as due to a call transfer). This is available only for FSK-based CID methods: (Bellcore, ETSI FSK, and ETSI FSK With PR). a) Bellcore/ETSI Onhook Post-Ring FSK First Ring b) ETSI Onhook Post-Ring DTMF First Ring c) ETSI Onhook Pre-Ring FSK/DTMF Polarity Reversal CAS (DTAS) d) Bellcore Onhook FSK w/o Ring OSI FSK DTMF DTMF/ First FSK Ring FSK e) ETSI Onhook FSK w/o Ring Polarity Reversal CAS (DTAS) FSK f) Bellcore/ETSI Offhook FSK CAS (DTAS) Wait For ACK FSK Silence Suppression and Comfort Noise Generation Voice Activity Detection (VAD) with Silence Suppression is a means of increasing the number of calls supported by the network by reducing the required bandwidth for a single call. VAD uses a 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. Silence suppression is configured in the Line and PSTN Line tabs. See "Linksys ATA Routing Field Reference," on page 86. Linksys ATA Administration Guide 48