Polycom IP331 Owner's Manual page 18

Cordless Phones:
This diagram depicts the setup options for Cordless Phones.
Cordless phones can be used in conjunction with Desk Phones or
they can be installed stand-alone.
Fax Adapter:
This diagram depicts the setup options for the Fax Adapter. The
Fax Adapter allows you to use your existing fax machine with the
Hosted PBX service.
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