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Voice over IP (VoIP)
Voice over IP (VoIP)
The term “Voice over IP” describes the usage of IP-based data networks for telephony. It is possible to distin-
guish between two different types of VoIP:
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Telephony via Internet provides cheaper charge-models for telephone services. For telephony directly via
the Internet, only the cost of data transmission is incurred. Various Gateway providers can provide
crossover into the PSTN (“Public Switched Telephone Network”) for a fee. As well as standardised pro-
tocols such as SIP and H.323, proprietary protocols such as the Skype network, are used. Voice and
service quality via Internet is often indeterminable, because you are dependent on the communication
lines of various service providers. which have been optimised for data communication
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Telephony via Intranet enables joint usage of existing infrastructure for telephony and for data communi-
cation. Integrating the two communication networks into a single communications network can provide
considerable savings. The Comfort Pro S gives users all the features of system telephony through its use
of an IP-based protocol. Furthermore, the standardised SIP protocol can also be used on the intranet. The
control of the data connections used makes it possible to define exactly the voice and service quality.
VoIP telephony over the Internet using the Comfort Pro S provides you with the following options (see also SIP
Telephony starting on page 98):
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You can use low-cost “SIP trunk lines” with your existing Internet connection
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You can use the services of a SIP gateway service provider to access the public telephone network
(PSTN)
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Automatic fallback (bundle overflow) to ISDN connections in case of the breakdown or over-occupancy of
the SIP connection
VoIP Telephony via intranet with the Comfort Pro S offers the following possibilities:
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Use of IP-based system telephones connected to Cat5 twisted-pair ethernet cables
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Use of IP-based system telephones via VPN, RAS, Branch or WLAN connections
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Using voice-data compression with compressing codecs, it is also possible to make multiple IP-based tel-
ephone calls simultaneously on a 64 kilobit/s ISDN line
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Use of PC-supported system telephones (so-called “Softphones”) without extra hardware costs