ComfyTel provides similar services as with Zadarma.com: you can create up to 3 SIP accounts which would be reachable from any of their PSTN access gateways. The only difference is the geographical coverage of those gateways, and also you get an 11-digit internal number (compared to a 5-digit number at Zadarma).
Also additional things which are not (yet) seen at Zadarma:
- you can forward calls to your Skype account. But last time I checked it, about 30% of calls were dropped. Probably their Skype gateway has limited capacity.
- You also get an 11-digit internal number which can be forwarded to your multiple SIP accounts at the same time.