Media5 Mediatrix 4104, Справочное руководство

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Voice & Fax Codecs Reference Manual (SIP Version)
Mediatrix 4104 85
4. Set the minimum and maximum packetization time values for the G.726 codec in the corresponding
drop-down menu.
The packetization time (also called packetization period or ptime) is the duration, in ms, of the voice
packet.
• Minimum : Shortest packetization period allowed for the G.726 codec. Authorized
values start at 10 ms and come in discrete steps of 10 ms up to the one specified by
the corresponding
Maximum drop-down menu.
• Maximum : Longest packetization period allowed for the G.726 codec. Authorized
values go up to 100 ms, in discrete steps of 10 ms, and start at the one specified by the
corresponding
Minimum drop-down menu.
5. Click Submit if you do not need to set other parameters.
Fax Parameters
The Mediatrix 4104 handles G3 fax transmissions at speeds up to 14.4 kbps. Automatic fax mode detection
is standard on all lines. Real-Time Fax Over UDP with the T.38 protocol stack is also available.
The quality of T.38 fax transmissions depends upon the system configuration, type of call control system used,
type of Mediatrix units deployed, as well as the model of fax machines used. Should some of these conditions
be unsatisfactory, performance of T.38 fax transmissions may vary and be reduced below expectations.
A fax call works much like a regular voice call, with the following differences:
1. The fax codec may be re-negotiated by using a re-INVITE.
2. The goal of the re-INVITE is to allow both user agents to agree on a fax codec, which is either:
a. Clear channel (PCMU/PCMA or G.726) without Echo Cancellation nor Silence Suppression
(automatically disabled).
b. T.38.
3. Upon fax termination, if the call is not BYE, the previous voice codec is recovered with another re-
INVITE.
All lines of the Mediatrix 4104 can simultaneously use the same codec (for instance, T.38), or a mix of any of
the supported codecs. Set and enable these codecs for
each line.