If the user wants to use their old PSTN (regular phone) handset they can instead buy VoIP ATA's which will turn you old handset into a VoIP enabled one.
ATA stands for analogue telephone adapter, and turns old phone signals into VoIP digital ones with out having to buy VoIP handsets.

For ant kind of business VoIP application there is a need to buy VoIP handsets as they offer call quality and features that an ATA can and will never provide.

Buying a good reputable VoIP handset will give ant small business employing VoIP the ability to run multiple calls on the one line. This also means when you buy a VoIP handset you will be able to have call waiting/transfer to multiple extensions from the VoIP you buy and station around you business.

Care should be taken when you buy a VoIP hand set online as there are so many sites from which you can buy a VoIP handset that it needs to be compliant with the communications regulations in your nation. The amount of websites that you can buy VoIP handsets from is truly staggering and there is almost no nation without a site from which you can buy a VoIP handset.

Which VoIP handset you buy will depend on what features you wish it to have and what brand you want. Linksys and Snom both make a mean VoIP handset and prices range from a couple of hundred dollars into the thousands for the top of the line VoIP handset to buy.

Without doubt the linksys SPA-942 is a fantastic peice of VoIP hardware. We try to use them not only as a value for money objective but for ease of set up and overall quality.

The VoIP call quality we get is fantastic but the linsys spa-942 makes it just that little bit better. at around $250 you will not get higher functionality or quality in a peice of VoIP hardware.

We always welcome discussion here even from our so called competitors so if anyone else would like to argue

If you wish to buy VoIP ATA'S then there is almost no limit to the range with many good products out there.

There are also many good reviews online to sort out what to buy in the way of VoIP products,try searching for VoIP hardware forums to get some user reviews on exactly what VoIP products to buy from VoIP boffins who love nothing more than to review a product warts and all.

If you buy a VoIP handset rather than a VoIP ATA then  make sure you get a power supply with it as some VoIP handsets are powe over ethernet only and if you do not have this facility then it will not work for you.
Some VoIP phone manufacturers charge extra to buy the VoIP handset power supply seperately as well so be wary of this when you choose to buy a VoIP handset.

In summary i belive it is better to buy VoIP handsets than to buy an ATA and run your old phone, it is only a couple of hundred dollars to buy a VoIP handset and it still cost half that to buy an ATA so you may as well bite the bullet and buy a VoIP handset to go with the new technology.