Polycom 1725-32504-001 - Manual (Page 34)

User Guide for the Polycom CX300 Desktop Phone
Safety Notices - 4
Safety and Compliance (Continued)
CE
This Polycom CX300 has been marked with the CE mark. This mark indicates compliance with EEC Directives
2004/108/EC and 2006/95/EEC. A full copy of the Declaration of Conformity can be obtained from Polycom Ltd,
270 Bath Road, Slough, Berkshire, SL1 4DX, UK.
Australia S004 Compliance
The user should be aware that, under certain operating conditions, the handset earpiece may retain small metallic
objects. If this occurs, these objects should be removed before using the handset.
New Zealand, Telepermit, CX300 USB Telephone, PTC 220/10/002
PTC General Warning
The grant of a Telepermit for any item of terminal equipment indicates only that Telecom has accepted that the item
complies with minimum conditions for connection to its network. It indicates no endorsement of the product by
Telecom, nor does it provide any sort of warranty. Above all, it provides no assurance that any item will work
correctly in all respects with another item of Telepermitted equipment of a different make or model, nor does it imply
that any product is compatible with all of Telecom's network services.
The CODEC and Optimum Packet Size for transmission through the Public Switched Telephone Network
(PSTN)
Because of the extensive delay already experienced when calling cellular and international networks, Telecom
Access Standards recommends the use of 20mS or less packet length when passing packets through the PSTN.
The use of G.711 codecs and 20mS or less packet length is critical to maintaining delay times which comply with
PTC220 requirements (<50mS).
Echo cancellation
Echo cancellers are not normally required in the Telecom PSTN because geographic delays are acceptable where
CPE return loss is maintained within Telepermit limits. However, those private networks making use of Voice over
IP technology are required to provide echo cancellation for all voice calls. The combined effect of audio / VoIP
conversion delay and IP routing delay can cause the echo cancellation time of 64 mS to be required.