SpectraLink NetLink Wireless Telephones Best Practices White Paper Wireless Telephone manual

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6.0NetLink Wireless Telephones and Subnets

Subnets are used to create a boundary between network segments. Although these boundaries are logical, they become somewhat of a physical boundary for mobile network devices moving throughout the enterprise. When a device with an established IP data stream (such as with an active phone call) attempts to roam across a subnet boundary, it needs to obtain a valid IP address within the new subnet. During this process the data stream cannot be re-established automatically and the connection (voice call) is dropped. In the case of the NetLink Wireless Telephones, the handsets should be power-cycled to obtain a new DHCP address. The handsets can automatically recover in the new subnet from a lost network connection with the original subnet, but the 40-second failure and recovery time generally warrants cycling the power.

Some APs, Ethernet switches, and third-party devices have implemented methods to facilitate device mobility. While these methods are transparent to the client device, they often cause enough delay and latency to manifest poor voice quality. In addition, many of these methods do not work well under loaded conditions, such as might be experienced with a large number of highly mobile wireless voice users.

NetLink Wireless Telephones must reside within the same subnet as the source of the SpectraLink Voice Priority (SVP) control. SVP can be controlled from a NetLink Telephony Gateway, a NetLink SVP Server, or a combination of the two. Because the NetLink SVP Server can only operate in a single PBX interface mode, Wireless Telephones cannot operate with a NetLink Telephony Gateway and in a native IP interface to an IP telephony server on the same NetLink SVP server. All SVP Servers on the same subnet must operate in the same PBX interface mode (either native IP or through NetLink Telephony Gateways).

There are additional subnet requirements for NetLink Wireless Telephones based on the infrastructure components that are used.

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