You could try DIDLogic (
http://www.didlogic.com/). I am a happy customer, as I can:
- Rent an inbound number for each of the countries that are important to me
- Set up multiple SIP accounts to use for outbound calls (much lower per minute rates than Skype or Rebtel)
- Set up one or more of those SIP accounts to ring when I get an incoming call, even doing it in sequence if I want
- Set the caller ID on outbound calls to whatever I want (e.g. my normal mobile number, or one of my rented incoming numbers) on a per-SIP-account basis
I use GroundWire on iOS as my SIP client. There are cheaper options. GroundWire is great, in part because they use Push notifications, but this requires you to trust their server with your SIP credentials.