Media5 Mediatrix 4104, Reference Manual

Page: 377 / 466

Fax Issues Reference Manual (SIP Version)
Mediatrix 4104 355
D
ESCRIPTION
: When making a 3-way conference, part of the conversation is lost, resulting in a choppy voice.

P
OSSIBLE
C
AUSE
: The packetization period (ptime) is not the same for all the participants of the
conference, which causes the choppy voice issue.
S
OLUTION
: For better results, Media5 recommends to set the packetization period of all participants of
a 3-way conference to 30 milliseconds. See “Packetization Time” on page 232 for more information on
how to set the packetization period of the Mediatrix 4104.
D
ESCRIPTION
: Unable to establish a call from the Mediatrix 4104 to a user agent such as an IP phone, a
gateway or another access device.

P
OSSIBLE
C
AUSE
: When the Mediatrix 4104 – with its T.38 capability enabled – tries to establish a call
with a user agent that does not support T.38, this a user agent rejects the call instead of ignoring the
capability it does not support, i.e., T.38.
S
OLUTION
: Disable the T.38 capability in the Mediatrix 4104. See “T.38 Fax” on page 252 for more
details.
Fax Issues
The following gives information pertaining to faxes. This includes a list of fax models tested with the Mediatrix
4104 and some specific issues the unit may encounter.
D
ESCRIPTION
: “Poor line condition” error during a fax transmission.

P
OSSIBLE
C
AUSE
: The analog transmission between the fax machine and the Mediatrix 4104 is flaky,
preventing the fax transmission to terminate properly. This problem is known to occur with some fax
machines and it can also occur with a few fax modems.
S
OLUTION
: Set the Input sound level to -6 dB . If this still does not solve the problem, try the +6 dB value.
See “User Gain” on page 244 for more details.
D
ESCRIPTION
: Unable to send a fax in T.38 and Clear Channel.

P
OSSIBLE
C
AUSE
: To properly send faxes, both units must be configured with the same settings. If you
are attempting to send a fax and the transmission fails, there could be many reasons for this, but most
likely the fax codec settings are at fault. The following explains the logic behind fax transmissions.
When transmitting a fax, Unit A first verifies if Unit B supports the codec you have set in Unit A. If the
codec is supported, the fax should be transmitted properly.
If the fax codec is not supported by Unit B, Unit A tries to find a common preferred G.711 clear channel
codec between the two units. If Unit A finds one, it uses this common clear channel codec and the fax
should be transmitted properly. If there are no common clear channel codecs between the units, the fax
transmission fails.
S
OLUTION
: To avoid fax transmission problems, configure both units with the same T.38 and clear
channel settings and the fax should be sent properly.