Medias Mediatrix 1204, Reference Manual

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Fax Issues Reference Manual (SIP Version)
Mediatrix 1204 285
D
ESCRIPTION
: I make a call from my PBX extension, but when I dial, the DTMFs are not recognized and the
call does not work.
P
OSSIBLE
C
AUSE
: When the Mediatrix 1204 seizes a line on the PBX, it needs a DTMF detection delay
of 250 ms - 300 ms before the PBX sends the DTMFs, or they are not recognized.
S
OLUTION
: Be sure that the PBX system does not send the DTMFs before the FXO takes the line (DTMF
detection delay of 250 ms - 300 ms).
P
OSSIBLE
C
AUSE
: When the dial tone detection feature and/or the line fault detection feature is disabled,
the Mediatrix 1204 sends the DTMFs too quickly on the SCN or to another device. The DTMFs are thus
not recognized.
S
OLUTION
: This problem is equipment-dependent. You must modify the pre-dial delay (in the
analogScnGwPreDialDelay variable) so that the DTMFs are not sent too quickly. Mediatrix suggests a
delay of 700 ms.
Fax Issues
The following gives information pertaining to faxes. This includes a list of fax models tested with the Mediatrix
1204 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 1204 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 212 for more details.
D
ESCRIPTION
: Unable to send a fax in T.38 and Clear Channel.
P
OSSIBLE
C
AUSE
: This applies in the case where the Mediatrix 1204 tries to reach another Mediatrix
1204 or any other IP endpoint. 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.