Save Bandwidth / Enable voice packet compression For GSM Gateway

[ralezjohn]

please gudie me how can we enable voice packet compression in Asterisk/Voipswitch with G729/G723 codecs baiscally i want to compress voice packets in to 8/10kbps how can i do this please guide me awaiting thanks.

[Daniele Giordano]

Select G729 and G723 as preferred codecs.

Asterisk example:

[general]

allowsubscribe=yes

notifyringing=yes

subscribecontext=blf

callcounter=yes

counteronpeer=yes

notifycid=ignore-context

srvlookup=yes

context=default                                          ; Default context for incoming calls

allowguest=no                                           ; Allow or reject guest calls (default is yes)

localnet=192.168.2.0/255.255.255.0            ; RFC 1918 addresses

nat=yes                                                    ; there is not NAT between phone and Asterisk

dtmfmode=RFC2833                                  ; either RFC2833 or INFO for the BudgeTone

relaxdtmf=yes

context=default

allowtransfert=yes

language=it

binport=5060

bindaddr=0.0.0.0

disallow=all

allow=g729     ;in * require license see http://www.voip-info.org/wiki/view/Asterisk+G.729+pass-thru

allaw=G723.1   ;in * require license see http://www.voip-info.org/wiki/view/Asterisk+G.723+pass-thru

Cisco voice gateway example:

voice class codec 10

codec preference 1 g729r8

codec preference 2 g729br8

codec preference 3 g723ar63

codec preference 4 g723ar53

codec preference 5 g723r63

codec preference 6 g723r53

Regards.

[ralezjohn]

Thanks bro for reply,

can you please tell me how mcuh bandwidth that i will need with that method for 32 Ports with g729 codect, and i am using GOIP GSM Gateway...and may ihave your skype ?

[Daniele Giordano]

The bandwidth used during a call is the sum of some parameters:

audio codec (e.g. G.729) + RTP header + UDP header + IP header + layer 2 header (e.g. ethernet).

A call in G.729 over ethernet uses 31.2 Kbps per direction:

A -----------> B 31.2 Kbps

A <----------- B 31.2 Kbps

So, how many concurrent calls do you need?

32 * 31.2 kb/s =  about 1 Mbit/s upload and download.

You can reduce bandwidth consumption enabling voice activity detection (VAD or silence suppression). In this case no packets are sent during silence. This technic could decrease the quality of a call introducing a little "silence hole" at the begining of the speak.

You can find more info here: http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080094ae2.shtml

Regards.