ARA-1 Operations Manual
3-12
INTEROPERABILITY NOW
its
Send Radio COR/AUX Status
function enabled (for example, a SIP Phone). If these other
devices will be used, set the ARA-1 Network COR Type to either
RTP VOX
or
RTP
VMR
.
Both
RTP VOX
and
RTP VMR
make use of the COR status information from
linked ARA-1s, but also properly link with non-ARA-1 devices. When either of these modes is
selected, the ARA-1 will use both functions (the COR status
or
VOX; the COR status
or
VMR)
to validate network audio. Select between these two options using the same reasoning as you
would when choosing between VOX and VMR.
NOTE:
The RTP extension header used to transfer COR/AUX status is not part
of the full common standard and, therefore, there is a possibility that another SIP
device may be using this header for some other purpose. Two conditions may
result:
(1) An incompatible SIP device will misinterpret the COR/AUX extension header
sent from the ARA-1. Most likely, the device will interpret the status information
as audio. Clicking noises may result in the device’s audio output.
(2) An incompatible SIP device will send a non-standard RTP extension header
that is misinterpreted by the ARA-1. This may cause the ARA-1 to signal the
associated radio to key inappropriately.
Use the following guidelines when deciding which Network COR types to use:
•
If all end devices are radios interfaced by ARA-1s, use RTP Header as the Network COR
type in all ARA-1s and enable the
Send Radio COR/AUX Status
SIP setting in all ARA-
1s.
•
If the network consists of mixed devices, for example, multiple ARA-1 units as well other
SIP devices such as SIP Phones or softphones, and these devices have no
incompatibilities with SIP extension headers use either
RTP Header + VOX
or
RTP
Header + VMR
as the Network COR type in all ARA-1s and enable the
Send Radio
COR/AUX Status
SIP setting in all ARA-1s.
•
If the network consists of mixed devices, for example, multiple ARA-1 units as well other
SIP devices such as SIP Phones or softphones, and these devices have SIP extension
header incompatibilities, do not use any of the Network COR Types that include RTP.
Instead use one of the other settings as the Network COR type in all ARA-1s and disable
the
Send Radio COR/AUX Status
SIP setting in all ARA-1s.
The next setting—
SIP Actions
—should be selected when controlling the ARA-1’s PTT output
via DTMF over the network. See Section 0 for instructions on how to configure SIP Actions.
The next network COR type option is
Packet
. When
Packet
is selected, the ARA-1’s decision as
to when to key the radio is based upon the presence or absence of audio RTP packets. When the
ARA-1 is receiving audio RTP packets, it will activate PTT and key the radio. When it stops
receiving audio RTP packets, it will deactivate PTT thus unkeying the radio. This feature must
be used in conjunction with silence suppression on the remote device.
When
Packet
COR is enabled, the
Network COR VOX/VMR/Packet Hang Time
setting described
in Section 3.3.5.3 is be used to adjust how long PTT remains active after receiving the last audio
