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Voice over IP (VoIP) SIP Telephony
SIP Telephony
The SIP Internet (Session Initiation Protocol) protocol provides you with a low-cost, standardised option for tel-
ephoning via IP-based networks. Comfort Pro S enables you to use external SIP telephone connections (“SIP
trunk lines”).
External SIP Connections
The PBX Configuration : Trunks : Route menu gives you the option of making an SIP connection on a normal
ISDN line in case of bundle overflow, breakdown or over-occupancy. You can also set up your system to route
certain types of calls, such as international calls, to an SIP connection.
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Note: You will need a Media Gateway card for SIP telephony.
You will also need a fast Internet connection such as DSL for SIP telephony.
You will also usually need the services of a SIP provider. A SIP provider operates a special server (the SIP Reg-
istrar) to handle connections. The SIP provider also operates a gateway to the ordinary telephone network
which users pay to use and which enables the SIP provider to provide calls to the telephone network.A SIP
connection can also accept incoming calls from the telephone network.
The same voice transmission techniques as those explained in Fundamentals starting on page 91 are used
for SIP telephony. SIP telephony has the following distinctive features:
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Subscribers are identified through an e-mail-like “SIP ID” such as 12345@domain.net or name@sip-pro-
vider.com.
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SIP transmits dialling numbers always in a single data package (block dialling). Dialling can therefore be
concluded with the hash key
#
on the system terminal, or the end of the number will be indicated by a
time-out. The value for this time-out can be defined for each SIP provider separately.
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You must log on (“Login”) to the SIP registrar before you can use SIP telephony. Use the Comfort Pro S to
manage important information for the registration (user name and password) of one or more SIP
accounts. It is possible to make several calls simultaneously using a single SIP account.