Network guidelines
Remote IP Feature Phone Installation Manual
F.2
WAN
•
Connection types
–
We recommend a dedicated or Point-to-Point high bandwidth circuit. For example a point-to-point
T-1, ISDN, or a Frame Relay connection with a high CIR.
1
When used with such a connection the
Remote IP Feature Phone will provide consistent high voice quality.
–
A remote connect over the public Internet cannot be expected to provide the same voice quality as
a dedicated or point to point connection. In troubleshooting audio problems over such connections,
verify that IP connection is or is not the source of the problem. Bandwidth and/or latency may be
the cause of the problem. If so, this cannot be corrected within the Remote IP Feature Phone or
PBX. The customer’s ISP has control over these issues. An upgrade of the customer’s IP access
may be required.
•
Bandwidth
–
Insure that the bandwidth for the voice will be available. The easiest way to do that is to attach
sniffer software (such as
Esi-Networx
) to the connection and gather an hour’s worth of stats during
the busiest time of the day. Record the peak number and multiply by 2. Now take the number of
proposed talk paths and multiply by 22kbps. Add those two numbers together. For example, the
customer has a 256 Kbps DSL line and, during peak times, has a total of 130K of traffic. He wants
12 talk paths. 12*22=264Kbps. 264+260=524Kbps. He will need to upgrade his line.
–
If the customer can, it would be preferable to get a CIR for the bandwidth that the customer will
need from his provider.
–
If possible, all the remote sites or Remote IP Feature Phone’s service providers work off the same
backbone provider.
•
Firewall issues
–
If the customer is using a firewall or proxy of some kind, you must have access to open up the
UDP ports for incoming and outgoing traffic. Make sure to set the customer’s expectation that, if
they are going through a firewall, the installer must have access to open UDP ports on the firewall.
If the customer is not comfortable with that, the customer will have to run the phones on a
separate network that doesn’t use the firewall.
•
Router issues
–
All UDP ports for the phones can be opened for incoming and outgoing traffic. This will mainly be
the case for NAT enabled routers.
–
Make sure that the networks that are to be used for the Remote IP Feature Phones or for Esi-Link
are not two private networks away from the public network. This will mainly be the case for newer
DSL and cable modem installations due to the fact that more and more ISPs are using private
networks and NATing new installations behind that private network. They do this to save IP
addresses.
–
You must know how to use
TRACERT
(traceroute) and/or
PING
to prove to the customer that the
issue they are having is a network issue. If they can
PING
a host on the remote network and vise
versa, the network is ok, but if they can’t, there are network issues. If you are seeing high latency
numbers from testing with
PING
, using
TRACERT
will show that there are too many hops between
networks. That is a network issue that the ISP will have to resolve before the multi-site capabilities
will operate properly.
Esi-Networx
provides even more information about network issues, and in an
easy-to-understand, graphical format.
1
Committed information rate.
