AudioCodes MediaPack 114 Manual do Utilizador descarregar pdf (Página 321)

Version 5.6 321 November 2008

SIP User's Manual 7. IP Telephony Capabilities

The network packets generated and received during the bypass period are regular voice

RTP packets (per the selected bypass coder), but with a different RTP payload type

(according to the parameters FaxBypassPayloadType and ModemBypassPayloadType).

During the bypass period, the coder uses the packing factor, which is defined by the

parameter FaxModemBypassM. The packing factor determines the number of coder

payloads (each the size of FaxModemBypassBasicRTPPacketInterval) that are used to

generate a single fax/modem bypass packet. When fax/modem transmission ends, the

reverse switching, from bypass coder to regular voice coder is performed.

To configure fax / modem bypass mode, perform the following configurations:

 IsFaxUsed = 0

 FaxTransportMode = 2

 V21ModemTransportType = 2

 V22ModemTransportType = 2

 V23ModemTransportType = 2

 V32ModemTransportType = 2

 V34ModemTransportType = 2

 BellModemTransportType = 2

 Additional configuration parameters:

• FaxModemBypassCoderType

• FaxBypassPayloadType

• ModemBypassPayloadType

• FaxModemBypassBasicRTPPacketInterval

• FaxModemBypassDJBufMinDelay

Note: When the device is configured for modem bypass and T.38 fax, V.21 low-

speed modems are not supported and fail as a result.

Tip: When the remote (non-AudioCodes’) gateway uses G711 coder for voice and

doesn’t change the coder payload type for fax or modem transmission, it is

recommended to use the Bypass mode with the following configuration:

• EnableFaxModemInbandNetworkDetection = 1

• FaxModemBypassCoderType = same coder used for voice

• FaxModemBypassM = same interval as voice

• ModemBypassPayloadType = 8 if voice coder is A-Law; 0 if voice coder

is Mu-Law

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AudioCodes MediaPack 114 Manual do Utilizador Página 321