I am now using VOIPStunt (
www.voipstunt.com) and have no complaints about the service so far.
I had to get an updated version of the driver for my VOIP USB Handset to gat full functionality but once installed that was it, it all works fine.
I paid a top-up of €10 to get all calls to UK and about 30 countries landlines for free, anytime and they provide an 0560 prefix number for folks to call you directly. International rates outwirth the free destinations appears competitive, audio quality on the calls made so far has been good and connection has been 100% so far. I used to use 18866 (same company) but now I will use VOIP and save the 4p connection charge.
Well worth a try...... cheaper than Skype and miles cheaper than most landline call inclusive deals.