Cisco SRP521W-K9-G1 Administration Guide - Page 92

6 92 Configuring Voice Configuring Voice Services Feature Adjustable Audio Frames Per Packet DTMF Relay Call Progress Tones Call Progress Tone Pass Through Echo Cancellation Description 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. RTP packets are configured in the SIP page. See SIP Page, page 120. The SRP 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 Relay is configured in the DTMF Tx Mode parameter in the Line pages. See Line Pages (1-2), page 156. The SRP has configurable call progress tones. Call progress tones are generated locally on the SRP so that 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. The Call Progress tones are configured in the Regional page, See Regional Page, page 136. This feature allows the user to hear the call progress tones (such as ringing) that are generated from the far-end network. Impedance mismatch between the telephone and the IP Telephony gateway phone port can lead to near-end echo. The SRP has a near-end echo canceller that compensates for impedance match. The SRP also implements an echo suppressor with Comfort Noise Generator (CNG) so that any residual echo is not noticeable. Echo Cancellation is configured from the Line pages. See Line Pages (1-2), page 156. Cisco SRP500 Series Services Ready Platforms Administration Guide (SRP520 Models)