I do suggest you to use this access number 08715525706 , there's no account to open..and you'll simply be billed by BT (if you're using BT service) on the 0871 access. It's 8p/ minute though, but I can easily connect and and quality is really good. No minutes wasted ! I've never encountered any problem with this service.
or
If you wish to call using pin numbers without buying a calling card, just use your mobile and text this keyword WETALK to 80041 for a £3 call credit, or text WETALK to 80550 for a £5 call credit. This credit amount will be taken from your mobile top-up balance or if you're prepaid account, it will be billed by your mobile provider. Access number will be sent to you by text after sending the said keyword. The charge is still 8p / minute for the access number.
I tried many cheaper services before, like 6-7p/minute but it was all wasted, and this one really works well.
I hope this helps.
