Voice over IP (VoIP)
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Voice over IP (VoIP)
The term “Voice over IP” describes the usage of IP-based data networks for telephony.
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 protocols 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 they are
dependent on the communication lines of various service providers. which have
been optimised for data communication
• Telephony via Intranet enables joint usage of existing infrastructure for telephony
and for data communication. Integrating the two communication networks 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. 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 OpenCom 130 / 150 provides you with the
following options (see also SIP Telephony starting on page 120):
• 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 tel-
ephone network (PSTN)
• 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 OpenCom 100 offers the following possibilities:
• Use of IP-based system telephones and of SIP telephones connected to Cat5
twisted-pair ethernet cables
• Use of IP-based system telephones and of SIP telephones via VPN, RAS, Branch or
WLAN connections
• Using voice-data compression with compressing codecs, it is also possible to make
multiple IP-based telephone calls simultaneously on a 64 kbit/s ISDN line
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