Avaya 4602SW+ web interface

I bought some Avaya 4602SW+ IP Phones “new-in-the-box”.
Following the instructions, I successfully use them as my Asterisk’s extension phones.
Unfortunately, I cannot access to the web interface of these phones (that, however, reply to Ping requests).
There is a configuration instruction to disable web interface (DisableWebAdmin), that defaults to 0 (that means “enable”). Furthermore, I explicitly set this instruction to enable web access (DisableWebAdmin 0), but without success.

I suspect that web access to 4602SW Ip Phones is possible only when these terminals are used in Avaya environment (PBX/Media server…)

Has anyone get web access to these Ip Phones using them as Asterisk extensions?

Many thanks in advance