Cisco SRP521W-K9-G1 Administration Guide - Page 88

6 Configuring Voice Configuring Voice Services Telephone/fax VV Services Ready Platform Ethernet Voice Internet gateway Service Provider VoIP Infrastructure V PSTN IP SIP proxy Phone 236741 The SRP maintains the state of each call made through the FXS interface and makes the proper reaction to user input events (such as on/off hook or hook flash). Because the SRP uses the Session Initiation Protocol (SIP), it is compatible with most Internet Telephony Service Provider offerings. SRP Voice Features The SRP is equipped with fully featured, programmable voice ports that can be custom provisioned within a wide range of configuration parameters. The following sections describe the factors that contribute to voice quality: • Supported Codecs • SIP Proxy Redundancy • Other SRP Voice Features Supported Codecs The SRP voice ports support the following codecs: Codec Description G.711 (A-law and mu-law) Very low complexity codecs that support uncompressed 64 kbps digitized voice transmissions at one through ten 5 ms voice frames per packet. These codecs provide the highest narrow-band voice quality and uses the most bandwidth of any of the available codecs. 88 Cisco SRP500 Series Services Ready Platforms Administration Guide (SRP520 Models)