Specifications

20 Chapter 1. Router Concepts
¥ Support for these voice gateways:
¥ Jetstream proprietary
¥ CopperCom proprietary
¥ ATM Forum Standards based (ATM Forum doc. VMOA-0145.00)
¥ Upstream traffic shaping (bandwidth management) of data when the telephony interface is active
¥ ADPCM or PCM voice encoding
¥ Local echo canceling (G.168)
This diagram illustrates how a Voice over DSL router connects both a phone system to the PSTN and a LAN to
the Internet over the same DSL line.
Configuring Your Telephony Services
Router models are available to support telephony services over both ATM and Frame Relay networks. For
telephony over ATM, the VPI/VCI is automatically set. (For most routers, it is set to 0*39). For telephony over
Frame Relay, the DLCI is automatically set to 22. The value must match your service providerÕs value. You can
change the value if necessary (see Trouble-Shooting Telephony Services, page 174
).
The phone number for each port is set by your voice service provider.
The phone dial tone is provided by the Class 5 switch via the voice gateway at your regional switching center
(RSC). All voice features of the switch are passed through to the phone set. The router supports the calling
services that you subscribe to from your service provider, such as call forwarding, caller ID, messaging, etc.
The bandwidth required for a voice call depends on whether PCM or ADPCM encoding is used. With PCM, each
voice call takes about 80 Kb of bandwidth (64 Kb plus overhead) when the phone goes off hook. With ADPCM,
only about 40 Kb is used (32 Kb plus overhead).
Configuration for voice and data routing can be performed using the Web-based Easy Setup configuration
program. For ATM standards-based gateways, the voice profile must match the configuration of the voice
gateway (see Changing Your Voice Profile, page 21).
You can use the Port Monitor GUI program to see the voice PVC and the last event message. To see LMI
statistics for a frame relay router, use the frame stats command (page 204). To see AAL2 statistics for the voice
gateway, use the voice l2stats command (Jetstream gateway only). For other commands to monitor telephony
services, see Trouble-Shooting Telephony Services (page 174).
Phone
system
LAN
DSLAM
ATM/Frame
Network
Router
Voice
Gate-
way
Class 5
Switch
Internet
PSTN
Voice
over
DSL
Router
DSL
Line
Phone lines
Ethernet