Potential Voip Problems - Avaya IP Office 3.2 Installation Manual

Potential VoIP Problems

It is likely that any fault on a network, regardless of its cause, will initially show up as a degradation in the
quality of VoIP operation. This is regardless of whether the fault is with the VoIP telephony equipment.
Therefore, by installing a VoIP solution, you must be aware that you will become the first point of call for
diagnosing and assessing all potential customer network issues.
Potential Problems
•
End-to-End Matching Standards:
VoIP depends upon the support and selection of the same voice compression, header
compression and QoS standards throughout all stages of the calls routing. The start and end
points must be using the same compression methods. All intermediate points must support
DiffServ QoS.
• Avoid Hubs:
Hubs introduce echo and congestion points. If the customer network requires LAN connections
beyond the capacity of the IP Office Unit itself, Ethernet switches should be used. Even if this is
not the case, Ethernet switches are recommended as they allow traffic prioritization to be
implemented for VoIP devices and for other device such as the Voicemail Server PC.
• Power Supply Conditioning, Protection and Backup:
Traditional phone systems provide power to all their attached phone devices from a single
source. In a VoIP installation, the same care and concern that goes into providing power
conditioning, protection and backup to the central phone system, must now be applied to all
devices on the IP network.
• Multicasting:
In a data only network, it is possible for an incorrectly installed printer or hub card to multicast
traffic without that fault being immediately identified. On a VoIP network incorrect multicasting will
quickly affect VoIP calls and features.
• Duplicate IP Addressing:
Duplicate addresses is a frequent issue.
•
Excessive Utilization:
A workstation that constantly transmits high traffic levels can flood a network, causing VoIP
service to disappear.
• Network Access:
An IP network is much more open to users connecting a new device or installing software on
existing devices that then impacts on VoIP.
• Cabling Connections:
Technically VoIP can (bandwidth allowing) be run across any IP network connection. In practice,
Cat5 cabling is essential.
Phone Installation Guide
IP Office 3.2
IP Office IP Phones
15-601042 Issue 11e (27th June 2006)
Page 9