Talkswitch CT.TS005.001101.UK - Manual (Page 130)

1 2 2 T A L K S W I T C H U S E R G U I D E • U K & I RE L A N D
2. Choose the right CODEC for your location
TalkSwitch supports 3 CODECs (compression algorithms). The default
CODEC is G.729 using approximately 25 Kbps bandwidth upstream and
25Kbps bandwidth downstream for each call. G.729 provides very good
call quality while minimizing bandwidth usage.
The G.726 (32Kbps) CODEC is a better quality solution compared to the
G.729 CODEC. However, it requires more bandwidth per call. A G.726 call
typically requires 50 Kbps bandwidth upstream and 50Kbps bandwidth
downstream for each call.
The G.711 CODEC provides the best voice quality. The trade-off is the
bandwidth requirement. G.711 calls typically requires up to 100 Kbps
bandwidth upstream and 100 Kbps bandwidth downstream.
If the power goes out, does the VoIP network stay up?
To ensure a reliable network connection, all elements of the VoIP network
should be connected to back-up power supplies (UPS). These elements might
include LAN switches, routers, firewalls, broadband connection devices (i.e.
cable modems, DSL modems), and VoIP devices. If the power goes out at the
Internet Service Provider, then no VoIP calls can be made. Calls can still be
placed over the regular phone lines.
What happens to VoIP if the IP network fails?
If the connection to the IP network is lost, it will not be possible to make
VoIP calls. Calls can still be placed over the regular phone lines.
Can a firewall prevent VoIP calls from passing through?
The purpose of a firewall is to control what kinds of traffic enter and leave
your network. The VoIP enabled TalkSwitch is designed with embedded
applications to help traverse firewalls properly. To allow VoIP calls to pass
through your firewall, you may need to use the port forwarding feature on
your firewall.
TalkSwitch default uses the following ports for VoIP:
Format Type Unit 1 Unit 2 Unit 3 Unit 4
RTP (voice): UDP 6000-6006 6010-6016 6020-6026 6030-6036
SIP
(signaling): UDP 5060 (This port is mapped to only one unit)