1/5/2007
EAG Gateway Series Administration Guidelines
MAG-06007 Rev. A
T.38 Jitter Size
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Setup T.38 jitter buffer value. Default value is 250ms. Valid value range is 40 ~ 1000.
T.38 Receive Gain
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This sets the T.38 receiving gain value. Default value is 1. Valid range is 0 ~ 4.
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Values 0 and 1:
mean -6dB and -3dB enhancement, respectively.
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Value 2:
means 0dB gain.
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Values 3 and 4:
means 3dB and 6dB enhancements, respectively.
T.38 Send Gain
This field sets the T.38 sending gain value. Default value is 2. Valid range is 0 ~ 4.
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Values 0 and 1:
mean -6dB and -3dB increment, respectively;
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Value 2:
means 0dB increment.
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Values 3 and 4:
mean 3dB and 6dB increment, respectively.
5.8.8
SIP Config
SIP divides the communications between the Server and the User Agent into two types: Request Line
and Status Line. Both messages include a message header and a SIP payload. Header indicates the
sender, the receiver, hops to route, etc., while payload describes the method to complete the session.
Line feeds are used to separate commands and parameters.
Request Line
SIP message sent from agent to server to initiate the session, including INVITE, ACK, BYE, CANCEL,
OPTION, and UPDATE.
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Message header:
Call-id;
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Parameters lines:
Via, From, To, Contact, Csq, Content-length, Max-forward, Content-type,
White Space, SDP, etc.
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Jitter is a major factor affecting the quality of IP calls. Jitter buffer is a software process that eliminates jitter
caused by transmission delays in Internet telephony (VoIP) network. As the jitter buffer receives voice packets,
it adds small amounts of delay to the packets so that all of the packets appear to have been received without
delays. Voice signals are sequential by nature (i.e., they must be played back in the order in which they were
sent) and the jitter buffer ensures that the received packets are in the correct order. Without a jitter buffer to
smooth the transmission, data can be lost, resulting in choppy audio signals. There are two types of jitter buffers
- dynamic and static. A static jitter buffer is hardware-based and configured by the manufacturer. A
software-based jitter buffer is called a dynamic jitter buffer and can be configured by the system or network
administrator.
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When detected signals are not strong enough over the network, we use signal gain parameter to increase the
strength of the signal.
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