Voice over IP (VoIP) Media Gateway (MGW)
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9.1.6 Useful services
The type of data compression used for VoIP prevents these types of connections
from using certain services. Take these notes into account especially if you want to
use connections made via Q.SIG-IP or SIP:
■ ISDN data services can not be used
■ Faxes can only be sent using the uncompressed G.711 codec
■ DTMF dial tones are only received by the other party if the uncompressed
G.711 codec is used
■ Analogue modems can not be used
Tip: Configure the actual usage for the a/b ports, e.g. set them to
Fax or Data (analogue). Connections from and to these a/b
ports will then be made using uncompressed or ISDN connec-
tions where possible.
9.2 Media Gateway (MGW)
The Media Gateway transforms VoIP voice data into PCM audio data. This function
converts voice data between VoIP telephones and all other terminal types.
Without the Media Gateway, VoIP telephones can only exchange call data directly
with other VoIP telephones. Media Gateway functionality is also required for pro-
ducing dial tones and making external phone calls with a VoIP telephone. A Media
gateway card makes 8 channels available. One Media gateway channel should be
available for a maximum of 3 VoIP terminals.
The Media Gateway also takes over the routing function for external SIP connec-
tions, making 8 external SIP connections possible.
9.2.1 Software MGW
The system software of the OpenCom 100 provides one limited Media Gateway
function. Depending on system process utilisation and available system memory,
up to four MGW channels are available. The software MGW function will be auto-
matically activated when no Media Gateway card is present.
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