Here's the site: http://phone.bitcoincommons.org
The site is currently operating on testnet. You will need to configure your bitcoin client to operate on the testnet in order to participate in the testing. Here is a working testnet faucet if you need some testnet bitcoin.
During the testing phase, any amount of testnet bitcoin sent to the bitcoin address presented at the top of the web page will give you a 3 minute call credit. Have you called your mother recently? The minimum call duration is one minute.
Please post your comments/feedback to this thread or email to: phone AT bitcoincommons.org
Recommend a tor website or at least https for your current site. Otherwise I don't see why anyone would use this over free google voice calls.
Which country is the server running?