Avaya 3641 Installation, Configuration And Administration page 38

Part B: Avaya 3641/3645 Wireless IP Telephone
WEP
The handset supports Wired Equivalent Privacy (WEP) with both 40-bit and 128-bit
encryption.
38 Avaya Voice Priority Processor, Avaya 3641/3645 Wireless IP Telephone, Handset Administration Tool