Prestige 2602HW Series User’s Guide
Figure 49 SIP Redirect Server
9.2.3.4 SIP Register Server
ASIP register server maintains a database of SIP
9.2.4RTP
When you make a VoIP call using SIP, the RTP (Real time Transport Protocol) is used to handle voice data transfer. See RFC 1889 for details on RTP.
9.3 SIP ALG
The Prestige 2602HW is a SIP Application Layer Gateway (ALG). A SIP ALG allows VoIP calls to pass through NAT by examining and translating IP addresses embedded in the data stream. When a VoIP device behind the Prestige registers with the SIP register server, the Prestige translates the device’s private IP address inside the SIP data stream to a public IP address. You do not need to use STUN with a VoIP device that is behind the Prestige 2602HW.
9.4 Pulse Code Modulation
Pulse Code Modulation (PCM) measures analog signal amplitudes at regular time intervals and converts them into bits.
Chapter 9 Introduction to VoIP | 135 |