Overview of Voice over IP (VoIP)
4600 Series IP Telephones
2-7
However, this capability also has the advantage of making station number portability easier.
Assume a situation where the company has multiple locations (for example, Lon don and New
York), all sharing a corporate IP network. Users want to take their telephones from their offices in
London and bring them to New York. When users power up their telephones in the new location,
the local DHCP server will generally route them to the local switch, which denies service because
it knows nothing about these new users. However, with proper administration of the local D HCP
server, the telephone knows to try a second call server IP address, this one in Lond on. The user
can then be automatically registered with the London switch.
Chapter 4, Server Administration contains details on administration of DCHP servers for lists of
alternate call servers, router/gateways, and TFTP servers. For specific information, see DNS
Addressing, on page 4-31.
Security 2
In VoIP, physical wire is replaced with an IP connection. The connection is more mobile.
Unauthorized relocation of the IP telephone allows unauthorized users to send a nd receive calls
as the valid owner. For further details on toll fraud, refer to the DEFINITY® or MultiVantage™
documents in Related Documents, on page 1-5.
Any equipment on a data network, including a 4600 Series IP Telephone, can be the target of a
Denial of Service attack. Typically, such an attack consists of flooding the network with so many
messages that the equipment either spends so much time processing them that it cannot process
legitimate tasks, or the equipment overloads and fails. Although the 4600 Ser ies IP Telephones
cannot guarantee resistance to all Denial of Service attacks, each Re lease has increasing checks
and protections to resist such attacks while maintaining appropriate servic e to legitimate users.
4600 Series IP Telephones 2
Dual Connection Architecture 2
Releases 1.0 and 1.1 of the 4600 Series IP Telephones use dual connection architecture to
communicate with the DEFINITY® switch. In the dual connection architecture, tw o station
extensions must be administered for each telephone.
Single Connection Architecture 2
Release 1.5 and subsequent releases of the 4600 Series IP Telephones use single connection
architecture to communicate with the Avaya media server switch. In the single connection
architecture, only one station extension must be administered for each teleph one.