Cisco Systems UBR900 User Manual
Feature Overview
14
Cisco IOS Release 12.0(7)T
Note
To support voice configurations involving Cisco gatekeeper products using RAS, the headend
must have IP multicast enabled. The cable interface must be designated as the default for RAS to
discover the gatekeeper. The gatekeeper then resolves all dialed destinations sent to the RAS
protocol.
discover the gatekeeper. The gatekeeper then resolves all dialed destinations sent to the RAS
protocol.
SGCP Protocol Stack
The Cisco uBR924 cable access router supports Simple Gateway Control Protocol (SGCP), an
out-of-band signaling protocol that interacts with an external call agent (CA) to provide call setup
and teardown for VoIP calls made through the Internet or a local intranet. Using the call control
agent, SGCP communicates with the voice gateways, allowing you to create a distributed system that
enhances performance, reliability, and scalability while still appearing as a single VoIP gateway to
external clients. SGCP eliminates the need for a dial plan mapper and static configuration on the
router to map IP addresses to telephone numbers because this function is provided by the external
call agent.
out-of-band signaling protocol that interacts with an external call agent (CA) to provide call setup
and teardown for VoIP calls made through the Internet or a local intranet. Using the call control
agent, SGCP communicates with the voice gateways, allowing you to create a distributed system that
enhances performance, reliability, and scalability while still appearing as a single VoIP gateway to
external clients. SGCP eliminates the need for a dial plan mapper and static configuration on the
router to map IP addresses to telephone numbers because this function is provided by the external
call agent.
In architectures using the SGCP protocol stack, the session application implements the gateway
functionality defined to support both trunk and residential gateways. The Cisco uBR924 functions
in this mode as a residential gateway with two endpoints.
functionality defined to support both trunk and residential gateways. The Cisco uBR924 functions
in this mode as a residential gateway with two endpoints.
SGCP can preserve Signaling System 7 (SS7) style call control information as well as additional
network information such as routing information and authentication, authorization, and accounting
(AAA) security information. SGCP allows voice calls to originate and terminate on the Internet, as
well as allowing one end to terminate on the Internet and the other to terminate on a telephone or
PBX on the PSTN.
network information such as routing information and authentication, authorization, and accounting
(AAA) security information. SGCP allows voice calls to originate and terminate on the Internet, as
well as allowing one end to terminate on the Internet and the other to terminate on a telephone or
PBX on the PSTN.
Note
The uBR924 cable access router supports both H.323 and SGCP call control, but only one
method can be active at a time.
Voice Specifications
Table 2
Cisco uBR924 Cable Access Router Voice Specifications
Metric
Value
Loss (between DCS and BTI gateway)
Nominal: 4 dB ±.5 dB (off hook)
Nominal: 9 dB ±.5 dB (on hook)
Nominal: 9 dB ±.5 dB (on hook)
Attenuation distortion:
DCS <> BTI (200Hz-3.5kHz)
BTI<> DCS (304 Hz-3004Hz)
DCS -> BTI (204 Hz-3004 Hz)
DCS <> BTI (200Hz-3.5kHz)
BTI<> DCS (304 Hz-3004Hz)
DCS -> BTI (204 Hz-3004 Hz)
Nominal:
+1 dB/-3 dB
±0.5 dB
±0.5 dB0
+1 dB/-3 dB
±0.5 dB
±0.5 dB0
Idle channel noise
<= 18 dBmC (noise shall not exceed)
Signal to C-notched noise
>= 35 dB
Inter-modulation distortion:
R2
R3
R2
R3
>= 52 dB
>= 52 dB
>= 52 dB
Single frequency interference:
0 to 12 kHz
0 to 4 kHz
0 to 12 kHz
0 to 4 kHz
<= -28 dBmO
<= -40 dBmO
<= -40 dBmO