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H323 Telephone Installation
Page 7
Issue 23e (Friday, February 15, 2019)
IP Office™ Platform 11.0
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IP Office H.323 IP Phones: Supported H.323 IP Phones
1.3 System Capacity
System capacity encompasses the number of configurable phone extensions and the number of simultaneous IP phone
calls.
Extension Capacity
The maximum number of H.323 IP phones supported depends on the type of system.
IP500 V2 systems support up to 384 extensions. To find the capacity for IP phones subtract the number of physical non-
IP extensions ports in the system, ie. extension ports on the IP Office control unit and any external expansion modules.
Note however that these systems only support a maximum of 148 VCM channels which may also restrict the number of
simultaneous VoIP calls, see below.
For IP Office Server Edition systems, the IP extension capacity depends on the server type. Refer to the
"IP Office
Capacity Guidelines"
document.
Call Capacity
There are a number of situations where the IP500 V2 system needs to provide a voice compression channel in order for
an IP phone to make calls. These channels are provided by
(VCMs) installed in the
system. The number of VCM channels required and how long the channel is required depends on a number of factors.
A simple summary is:
·
A VCM channel is required during call setup.
·
The VCM channel is released if the call is to/from another IP device using the same compression codec (the
supported VCM codecs are G.711, G.729 and G.722).
·
The VCM channel is used for the duration of the call when the call is to/from/via a non-IP device (extension or
trunk line).
·
It should be remembered that VCM channels are also used for calls from non-IP devices to IP lines if those are
configured in the IP Office system (IP, SIP and SES lines).
·
Calls from IP phones to the IP Office voicemail server use a VCM channel.
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