I need some articles written for VoIP (voice over IP) Telephone Services

Kind of writing: Technology
Num. of articles: 5
Words per article: 500-700
Industry: Technology
Topic: Voice Over IP
Tone: Formal/Professional
Outline & Structure: I am currently building a website for my client The homepage of the site is here: http://192.185.121.224/~intovoip/

The target customers are small, medium and also large scale businesses that are looking to either replace their standard telephone system (or telephones) with VoIP Internet systems or startup companies. We have identified specific keywords that we need articles written for that both explain the terminology but will also highlight the benefits for purchasing the telephones and systems so they will be a cross between explaining the basic technical aspects along with copy writing to get them to contact for more information.

I need articles on the following:
What is VoIP - This will explain what VoIP is so the customer understands the benefits for having it.
Internet Phones - This will explain what internet phones are and their capabilities.
Hosted VoIP/IP Telephony - This will explain what Hosted VoIP (IP Telephony is a synonym so this term should be used also) is and the benefits for having it.
PABX Replacement - This article will explain the benefits from replacing current P(A)BX systems with VoIP.
Internet Office Phone Systems - Again similar to Internet phones but more directed at larger companies that will benefit complete systems such as conferencing etc.
Extra notes: My client will add more of the technical aspects of their service to the articles but I need a framework that is grammatically correct for English U.K. and speaks in the same tone as the homepage: http://192.185.121.224/~intovoip/