Mitel 5560 IPT none Specifications download pdf (Page 280)

Engineering Guidelines

266

Resources required

• T.38 is a licensable option. Licenses can be purchased in increments of four.

• A maximum of 56 T.38 sessions are supported on a DSP II card.

• At the start of a fax call an echo canceller is used. Once the call switches to T.38 mode,

the echo canceller is placed in by-pass mode but continues to be allocated for the duration

of the call.

• At the start of a call a Fax Tone/V.21 detector is used to determine if the call is a fax call.

After 60 seconds the detector is relinquished.

DSP provisioning

• At start up, the system provisions the DSP II card with T.38 first, and then G.729.

• More T.38 or G.729 licenses can be purchased than the system hardware configuration

supports. This allows licenses to be purchased prior to the installation of the DSP II card.

• A system reboot is required for licensing changes to take effect.

Zones

• Zones are used to control where compression and Bandwidth Management are used.

• Zones can also be used to control where T.38 will be used. For instance, in some cases

there may not be enough T.38 resources available for all Fax calls, in these situations the

Administrator may want some Fax calls to be handled as G.711 Pass Through so that other

specific routes can be guaranteed the use of T.38 resources.

• As a general rule, T.38 should be used to transport Faxes between different zones.

• Networks and endpoints that communicate with each other over a WAN should be config-

ured in different zones to allow for the use of T.38.

• The use of compression and T.38 within a zone can be configured independent from one

another.

• In ESM there is form called the "Fax Service Profiles". This form allows the administrator

to define how inter-zone (between zones) and intra-zone (within a zone) faxes will be

handled.

• There is a pre-programmed default profile for both inter-zone and intra-zone traffic.

• The Administrator has the ability to create custom profiles for intra-zone traffic. Custom

profiles cannot be created for inter-zone traffic.

• If two 3300s are located in the same zone and have different Intra-zone T.38 settings

configured. The system will attempt to place the call with the T.38 profile that uses the least

amount of bandwidth.

• The Fax Service Profiles form can be shared via SDS. Sharing restrictions do not apply to

this form.

Note: T.38 licenses are only required to allow an ICP to originate or to terminate Faxes

sent over IP or SIP trunks, T.38 licenses are not required on an intermediate or tandem

ICP.

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Mitel 5560 IPT none Specifications Page 280