Technical data

Architecture and System Requirements

EN4442EN00EN_0002

Siemens

Note that the bandwidth calculation is based on 70 bytes of overhead: RTP (12 bytes), UDP (8

bytes), IP (20 bytes), 802.1Q VLAN Tagging (4 Bytes), MAC (incl. Preamble, FCS, 26 Bytes).

2.5.5 Voice Activity Detection (VAD)

Voice activity detection conserves bandwidth in the IP network during pauses in speech and

can further reduce the required network bandwidth from 50% to 75% (see Section 6.9, “Voice

Activity Detection (VAD)” for more details).

Figure 2-1 VoIP Bandwidth Reduction Sequence

60ms 15% 73.3 Kbps

G.729A 20ms 350% 36.0 Kbps

40ms 175% 22.0 Kbps

60ms 117% 17.3 Kbps

G.723 (6.4) 30ms 291% 25.1 Kbps

60ms 146% 15.7 Kbps

90ms 97.2% 12.6 Kbps

Important

Bandwidth requirements assume Full Duplex operation!

When running Half Duplex, twice the bandwidth is required.

Encoding Sampling Time IP Overhead BW per Connection

Table 2-1 IP Overhead and BW per Connection