Voice over IP (VoIP)
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9. Voice over IP (VoIP)
The term “Voice over IP” describes the usage of IP-based data networks for tele-
phony. It is possible to distinguish between two different types of VoIP:
■ 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. optimised for data communication Voice and service quality via
Internet, is often indeterminable because you are dependent on the routes of
various service providers. which have been optimised for data communication
■ Telephony via Intranet enables joint usage of existing infrastructure for tele-
phony and for data communication. Integrating the two communication net-
works into a single communications network can provide considerable savings.
The OpenCom 100 gives users all the features of system telephony through its
use of an IP-based protocol. The control of the data connections used makes it
possible to define exactly the voice and service quality.
Telephony over the Internet using the OpenCom 100 provides you with the fol-
lowing options (see also SIP Telephony starting on page 107):
■ You can use low-cost “SIP trunk lines” with your existing Internet connection
■ You can use the services of a SIP gateway service provider to access the public
telephone network (PSTN)
■ Automatic fallback (bundle overflow) to ISDN connections in case of the
breakdown or over-occupancy of the SIP connection
■ With a M100-AT4 interface card (4 analogue trunk lines) you can also use the
external IP Gateway 1 for SIP telephony
VoIP system telephony with the OpenCom 100 offers the following possibilities:
■ Use of IP-based system telephones connected to Cat5 twisted-pair ethernet
cables
■ Use of IP-based system telephones via VPN, RAS, Branch or WLAN connections
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