CONFIGURATION FILES
CHAPTER 5
81
ECOTEL 3G 16.1. Revised: 1 March 2011.
VoipCompression=<list>
The compression to be used, in order of preference. At least one matching codec with the peer must be de-
fined.
Voice:
g729, g729a, g729b, g729ab
These codecs have a bit rate of 8 kbit/s (compression ratio 1:8). A stands for Annex A and B for
Annex B.
g72616, g72624, g72632
These ADPCM codecs have various bit rates: g72616 = 16kBit/s (compression ratio 1:4), g72624
= 24kBit/s and g72632 = 32kBit/s (compression ratio 1:2).
NOTE: G726 32kBit/s can also be signaled as G.721 by using the entry g721.
g728
The Codec has a bit rate of 16kBit/s (compression ratio 1:4).
g711a, g711u
These PCM codecs have a bit rate of 64kBit/s. No voice compression occurs. a stands for a-law
and u for μ-law.
g723, g723L
These codecs work with 30ms data frames. g723.1 uses a bit rate of 6.3 kbit/s, and g723L uses
a bit rate of 5.3 kbit/s to send RTP packets.
NOTE: This has no influence on the compression ratio of incoming RTP packets. Both sides must
be able to receive both ratios.
gsm
GSM-FR (full rate) has a bit rate of 13 kbit/s.
The following codecs are also possible: g721 (SIP only)
Fax: t38
T.38 (fax over IP) allows the transfer of fax documents in real time between 2 fax machines over
IP. Following fax detection during a call, the voice codec will switch to T.38.
Data: trp
Transparent or clear mode (RFC 4040). Transparent relay of 64 kbit/s data streams.
gnx64
ccd
Clear-channel signaling (as per RFC3108)
Define a special profile for data call origination or destination numbers. Bear in mind that echo cancelation
in this VoIP profile might be switched off (
VoipECE=no).
Table 5.22 route.cfg: VoIP Basic Parameters (continued)
VoIP Basic Parameters
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