I have added some documentation now to encourage more users to give it a try.
BTW, I have also added 2 forwarding rules on my own server - so if you have a SIP client, why not point it to sip:spam@cmeerw.org or sip:time@cmeerw.org (which will forward the requests to sip:166@voipfone.co.uk and sip:123@voipfone.co.uk).