Netcom NB9 - Manual (Page 23)

NB9/NB9W ADSL+ VoIP Router
YML790 Rev8
VOICE
About SIP & VoIP
Voice Settings
The NB9/NB9W has the ability to connect two regular telephones via the Phone1 and Phone2 ports on the
rear of the unit and provides a number of sophisticated call-management functions such as call forward, call
waiting, call transfer and so on. The following section provides further details of how to set up VoIP services,
and then how to use the advanced telephony functions offered by the NB9/NB9W.
Note: You can use separate VoIP accounts from your VoIP Service Provider but not separate accounts with different VSPs.
This means that you can configure your NB9/NB9W to provide two telephone extensions.
VoIP services are usually provided through a standard technology called SIP, briefly described as follows.
About SIP
SIP, the Session Initiation Protocol, is a signalling protocol for Internet conferencing, telephony, presence,
events notification and instant messaging. SIP is the Internet Engineering Task Force standard for
multimedia conferencing over the Internet. SIP is designed to address the functions of signalling and session
management within a packet-switched network. Signalling allows call information to be carried across
network boundaries while session management provides the ability to control the qualities and attributes of
an end-to-end call.
The Session Initiation Protocol is a peer-to-peer protocol. There are four components in the SIP standard:
• User Agent (UA)
• Proxy Server
• Registrar Server
• Redirect Server
In effect, this means that when you sign up for a VoIP account based on a SIP server, your ‘VoIP’ number and
account details are managed by the SIP server at the VoIP Service Provider premises; by entering your SIP
details (e.g. ‘sip.serviceprovider.com’) along with your VoIP/SIP account number and your account password,
you are ‘registered’ with the service and able to make VoIP calls in practically the same way as with a
traditional phone service (but for a much lower cost.)