it depends on what you want to do exactly.

your phone can also dial with uri feature over http.

so you could click a link to send the phone xml command to dial.

in that case your website has to be personalized - every user gets links to his own phone ip address

you would need a webserver and a website for your contacts.

or a form to dial the number.

uri freature is very simple and does not require any other software but a webserver.

http://www.cisco.com/en/US/docs/voice_ip_comm/cuipph/all_models/xsi/5_1/english/programming/guide/ip5_1ch3.html#wp1033350

lg

Arnulf