Linksys RTP300 User Guide - Page 24

Introducing Linksys Analog Telephone Adapters ATA Software Features Feature International Caller ID Delivery Secure Calls Adjustable Audio Frames Per Packet DTMF Call Progress Tone Generation Call Progress Tone Pass Through Echo Cancellation Description In addition to support of the Bellcore (FSK) and Swedish/Danish (DTMF) methods of Caller ID (CID) delivery, Linksys ATAs provide a large subset of ETSI-compliant methods to support international CID equipment. International CID is configured in the Line and PSTN Line tabs. See "Linksys ATA Voice Field Reference," on page 94. A user (if enabled by service provider or administrator) has the option to make an outbound call secure in the sense that the audio packets in both directions are encrypted. See "Secure Call Implementation" section on page 57. This feature allows the user to set the number of audio frames contained in one RTP packet. Packets can be adjusted to contain from 1-10 audio frames. Increasing the number of packets decreases the bandwidth utilized, but it also increases delay and may affect voice quality. See the RTP Packet Size parameter found in the SIP tab in the "Linksys ATA Voice Field Reference," on page 94. The Linksys ATA device may relay DTMF digits as out-of-band events to preserve the fidelity of the digits. This can enhance the reliability of DTMF transmission required by many IVR applications such as dial-up banking and airline information. DTMF is configured in the DTMF Tx Mode parameter found in the Line tabs. See the "Linksys ATA Voice Field Reference," on page 94. The Linksys ATA device has configurable call progress tones. Call progress tones are generated locally on the ATA device so an end user is advised of status (such as ringback). Parameters for each type of tone (for instance a dial tone played back to an end user) may include frequency and amplitude of each component, and cadence information. See the Regional tab in the "Linksys ATA Voice Field Reference," on page 94. This feature allows the user to hear the call progress tones (such as ringing) that are generated from the far-end network. See the Regional tab in the "Linksys ATA Voice Field Reference," on page 94. Impedance mismatch between the telephone and the IP Telephony gateway phone port can lead to near-end echo. The Linksys ATA device has a nearend echo canceller that compensates for impedance match. The Linksys ATA device also implements an echo suppressor with comfort noise generator (CNG) so that any residual echo is not noticeable. Echo Cancellation is configured in the Regional, Line, and PSTN Line tabs. See "Linksys ATA Voice Field Reference," on page 94. Linksys ATA Administration Guide 24