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CHAPTER
5-1
Cisco ATA 187 Analog Telephone Adaptor Administration Guide for SIP (Version 1.0)
OL-21862-01
5
Configuring Fax Services
The ATA 187 provides two modes of fax services that are capable of internetworking with Cisco IOS
gateways over IP networks. These modes are called fax pass-through mode and T.38 fax relay mode.
With fax pass-through mode, the ATA 187 encodes fax traffic within the G.711 voice codec and passes
it through the Voice Over IP (VoIP) network as though the fax were a voice call.
With T.38 fax relay mode, the ATA 187 supports the transmission of faxes, in real time, between two
standard fax terminals communicating over SIP networks. T.38 fax relay mode provides a more reliable
and error-free method of sending faxes over an IP network
Using Fax Mode
You can choose the preferred fax mode on the phone configuration page of the Unified CM
administration page. From the fax mode pull-down window, choose one of the following modes:
• Fax pass-through
• T.38 fax relay
You can set the Fax Error correction mode override values. From the fax mode pull-down window,
choose one of the following modes:
• On
• Off
• Default
You can also set the maximum fax rate values from the phone configuration menu by choosing one of
the values on the pull-down window.
Note When the fax mode is T.38 fax relay, Message Transfer Part (MTP) cannot be enabled.
Fax Modem Standards
Note V.34 is supported for modem only, not for fax.