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CODEC is an abbreviation of COmpress-DECompress, capable of coding or decoding a digital data stream or signal by implementing an algorithm. The object of the algorithm is to represent the high-fidelity audio signal with minimum number of bits while retaining the quality. This can effectively reduce the frame size and the bandwidth required for audio transmission.

(Take V72 for example)
The default codecs used on IP phones are summarized in the following table:



In addition to the codecs introduced above, IP phones also support codecs: G723_53, G723_63, G726-16, G726-24, G726-32, G726-40, GSM and iLBC. Codecs and priorities of these codecs are configurable on a per-line basis. The attribute “rtpmap” is used to define a mapping from RTP payload codes to a codec, clock rate and other encoding parameters.

The corresponding attributes of the codec are listed as follows:
1. Please don't change the rtpmap for each codec.
2. Codecs G726-16, G726-24 and G726-40 are not applicable to SIP - T19P and SIP - T21P IP phones.



To configure the codecs and adjust the priority of the enabled codecs on a per-line basis via web user interface:
1. Click on Account.
2. Select the desired account from the pull-down list of Account.
3. Click on Codec.
4. Select the desired codec from the Disable Codecs column and click -> . The selected codec appears in the Enable Codecs column.
5. Repeat the step 4 to add more codecs to the Enable Codecs column.
6. Click <- to remove the codec from the Enable Codecs column.
7. Click or to adjust the priority of the enabled codecs.



8. Click Confirm to accept the change.

The auto provisioning templates for Codec are as below:

For SIP - T20P/T22P/T26P/T28P/T4X IP phones:(Just edit priority and enable line.)
----------------------------------------------------
#!version:1.0.0.1
##account.X.codec.Y.xxx = . X is the sip account sequence; Y is the codec sequence. Please don't change Y in below syntax. ##
##(Take account 1 for example)##


account.1.codec.1.enable = 1
account.1.codec.1.payload_type = PCMU
account.1.codec.1.priority = 1
account.1.codec.1.rtpmap = 0

account.1.codec.2.enable = 1
account.1.codec.2.payload_type = PCMA
account.1.codec.2.priority = 2
account.1.codec.2.rtpmap = 8

account.1.codec.3.enable = 0
account.1.codec.3.payload_type = G723_53
account.1.codec.3.priority =0
account.1.codec.3.rtpmap = 4

account.1.codec.4.enable = 0
account.1.codec.4.payload_type = G723_63
account.1.codec.4.priority = 0
account.1.codec.4.rtpmap = 4

account.1.codec.5.enable = 1
account.1.codec.5.payload_type = G729
account.1.codec.5.priority = 3
account.1.codec.5.rtpmap = 18

account.1.codec.6.enable = 1
account.1.codec.6.payload_type = G722
account.1.codec.6.priority = 4
account.1.codec.6.rtpmap = 9

account.1.codec.7.enable = 0
account.1.codec.7.payload_type = iLBC
account.1.codec.7.priority = 0
account.1.codec.7.rtpmap = 106

account.1.codec.8.enable = 0
account.1.codec.8.payload_type = G726-16
account.1.codec.8.priority = 0
account.1.codec.8.rtpmap = 103

account.1.codec.9.enable = 0
account.1.codec.9.payload_type = G726-24
account.1.codec.9.priority = 0
account.1.codec.9.rtpmap = 104

account.1.codec.10.enable = 0
account.1.codec.10.payload_type = G726-32
account.1.codec.10.priority = 0
account.1.codec.10.rtpmap = 102

account.1.codec.11.enable = 0
account.1.codec.11.payload_type = G726-40
account.1.codec.11.priority = 0
account.1.codec.11.rtpmap = 105

account.1.codec.12.enable = 0
account.1.codec.12.payload_type = GSM
account.1.codec.12.priority = 0
account.1.codec.12.rtpmap = 3
----------------------------------------------------
For SIP - T19P/T21P IP phones:(Just edit priority and enable line.)

----------------------------------------------------
#!version:1.0.0.1
##account.X.codec.Y.xxx = . X is the sip account sequence; Y is the codec sequence. Please don't change Y in below syntax. ##
##(Take account 1 for example)##

account.1.codec.1.enable = 1
account.1.codec.1.payload_type = PCMU
account.1.codec.1.priority = 1
account.1.codec.1.rtpmap = 0

account.1.codec.2.enable = 1
account.1.codec.2.payload_type = PCMA
account.1.codec.2.priority = 2
account.1.codec.2.rtpmap = 8

account.1.codec.3.enable = 0
account.1.codec.3.payload_type = G723_53
account.1.codec.3.priority =0
account.1.codec.3.rtpmap = 4

account.1.codec.4.enable = 0
account.1.codec.4.payload_type = G723_63
account.1.codec.4.priority = 0
account.1.codec.4.rtpmap = 4

account.1.codec.5.enable = 1
account.1.codec.5.payload_type = G729
account.1.codec.5.priority = 3
account.1.codec.5.rtpmap = 18

account.1.codec.6.enable = 1
account.1.codec.6.payload_type = G722
account.1.codec.6.priority = 4
account.1.codec.6.rtpmap = 9

account.1.codec.7.enable = 0
account.1.codec.7.payload_type = iLBC
account.1.codec.7.priority = 0
account.1.codec.7.rtpmap = 106

account.1.codec.8.enable = 0
account.1.codec.8.payload_type = G726-32
account.1.codec.8.priority = 0
account.1.codec.8.rtpmap = 102
----------------------------------------------------

For SIP - T3 Series IP phones-V70:(Just edit priority and enable line.)

----------------------------------------------------
#!version:1.0.0.1
##File header "#!version:1.0.0.1" can not be edited or deleted.##
#Audio codecs for account 1 (Y ranges from 1 to 13).
#account.1.codec.y.enable =
#account.1.codec.y.payload_type =
#account.1.codec.y.priority =
#account.1.codec.y.rtpmap =

account.1.codec.1.enable = 1
account.1.codec.1.payload_type = PCMU
account.1.codec.1.priority = 1
account.1.codec.1.rtpmap = 0

account.1.codec.2.enable = 1
account.1.codec.2.payload_type = PCMA
account.1.codec.2.priority = 2
account.1.codec.2.rtpmap = 8

account.1.codec.3.enable = 0
account.1.codec.3.payload_type = G723_53
account.1.codec.3.priority =4
account.1.codec.3.rtpmap = 4

account.1.codec.4.enable = 0
account.1.codec.4.payload_type = G723_63
account.1.codec.4.priority = 0
account.1.codec.4.rtpmap = 4

account.1.codec.5.enable = 1
account.1.codec.5.payload_type = G729
account.1.codec.5.priority = 3
account.1.codec.5.rtpmap = 18

account.1.codec.6.enable = 1
account.1.codec.6.payload_type = G722
account.1.codec.6.priority = 4
account.1.codec.6.rtpmap = 9

account.1.codec.7.enable =
account.1.codec.7.payload_type =
account.1.codec.7.priority =
account.1.codec.7.rtpmap =

account.1.codec.8.enable = 0
account.1.codec.8.payload_type = G726-16
account.1.codec.8.priority = 0
account.1.codec.8.rtpmap = 112

account.1.codec.9.enable = 0
account.1.codec.9.payload_type = G726-24
account.1.codec.9.priority = 0
account.1.codec.9.rtpmap = 102

account.1.codec.10.enable = 0
account.1.codec.10.payload_type = G726-32
account.1.codec.10.priority = 0
account.1.codec.10.rtpmap = 2

account.1.codec.11.enable = 0
account.1.codec.11.payload_type = G726-40
account.1.codec.11.priority = 0
account.1.codec.11.rtpmap = 104

## Below syntaxs are special for some custom versions.##

account.1.codec.12.enable = 0
account.1.codec.12.payload_type = iLBC_13_3
account.1.codec.12.priority = 0
account.1.codec.12.rtpmap = 97

account.1.codec.13.enable = 0
account.1.codec.13.payload_type = iLBC_15_2
account.1.codec.13.priority = 0
account.1.codec.13.rtpmap = 97

----------------------------------------------------

For VP530 phones-V70:(Just edit priority and enable line.)

----------------------------------------------------
#!version:1.0.0.1

##File header "#!version:1.0.0.1" can not be edited or deleted.##
#Audio codecs for account 1 (Y ranges from 1 to 7).
#account.1.codec.y.enable =
#account.1.codec.y.payload_type =
#account.1.codec.y.priority =
#account.1.codec.y.rtpmap =

account.1.codec.1.enable = 1
account.1.codec.1.payload_type = PCMA
account.1.codec.1.priority = 2
account.1.codec.1.rtpmap = 8

account.1.codec.2.enable = 1
account.1.codec.2.payload_type = PCMU
account.1.codec.2.priority = 1
account.1.codec.2.rtpmap = 0

account.1.codec.3.enable = 1
account.1.codec.3.payload_type = G729
account.1.codec.3.priority =3
account.1.codec.3.rtpmap = 18

account.1.codec.4.enable = 1
account.1.codec.4.payload_type = G722
account.1.codec.4.priority = 4
account.1.codec.4.rtpmap = 9

account.1.codec.5.enable = 0
account.1.codec.5.payload_type = G723
account.1.codec.5.priority = 5
account.1.codec.5.rtpmap = 4

account.1.codec.6.enable = 0
account.1.codec.6.payload_type = AACLC
account.1.codec.6.priority = 6
account.1.codec.6.rtpmap = 102

account.1.codec.7.enable = 0
account.1.codec.7.payload_type = iLBC
account.1.codec.7.priority = 7
account.1.codec.7.rtpmap = 122

#Video codecs for account 1 (X ranges from 1 to 3)
#account.1.video_codec.xxxxx.enable =
#account.1.video_codec.x.priority =
#account.1.video_codec.x.payload_type =
#account.1.video_codec.x.rtpmap =
#account.1.video_codec.x.para =

account.1.video_codec.1.enable = 1
account.1.video_codec.1.priority = 1
account.1.video_codec.1.payload_type = H264
account.1.video_codec.1.rtpmap = 99
account.1.video_codec.1.para = profile-level-id=42800D; packetization-mode=0; max-mbps=11880

account.1.video_codec.2.enable = 1
account.1.video_codec.2.priority = 2
account.1.video_codec.2.payload_type = H263
account.1.video_codec.2.rtpmap = 34
account.1.video_codec.2.para = CIF=1; QCIF=1

account.1.video_codec.3.enable = 1
account.1.video_codec.3.priority = 3
account.1.video_codec.3.payload_type = mp4v-es
account.1.video_codec.3.rtpmap = 102
account.1.video_codec.3.para = CIF=1; QCIF=1; MaxBR=3840
----------------------------------------------------

Packetization Time

Ptime (Packetization Time) is a measurement of the duration (in milliseconds) of the audio data in each RTP packet sent to the destination, and defines how much network bandwidth is used for the RTP stream transfer . Before establishing a conversation, codec and ptime are negotiated through SIP signaling. The valid values of ptime range from 10 to 60, in increments of 10 milliseconds. The default ptime is 20ms. You can also disable the ptime negotiation.

To configure the Ptime on a per-line basis via web user interface:
1. Click on Account.
2. Select the desired account from the pull-down list of Account.
3. Click on Advanced.
4. Select the desired value from the pull-down list of PTime (ms).



5. Click Confirm to accept the change.

The auto provisioning template for ptime is as below:
-------------------------------------------
#!version:1.0.0.1
##account.X.ptime = . It configures the RTP packet time for account X ##
##(Take account 1 for example)##
##ptime= 0 (Disabled), 10, 20, 30, 40, 50 or 60. The default value is 20.

account.1.ptime =

-------------------------------------------

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