VoIP callback server (feature request)

[rybshik]

Looking for the following solution(s)
1) Callback for a local mobile phone.
Let’s say I have a cell phone with unlimited in-bound minutes.
To request a call-back, I dial a local (or 800-number) DID, which I own. This DID points to the SIP address of the incoming trunk of my callback server. The callback server looks at the CID of incoming calls and if it matches my cell phone number, then it rings back to my cell phone. It is important that the ring-back call is routed via a VoIP provider of my choice.

2) Callback for a remote international location. The previous scheme is extended as follows. The request for call-back is sent as SIP-call at the SIP address of the incoming trunk of the callback server. When the callback server receives such a request, it matches the SIP address of the sender and, based on it, rings back to a PSTN number associated with the SIP address. Again, the ring-back call is routed via a VoIP provider of my choice.

Comment: Given cheap mobile rates in the USA, call-back does not provide much savings there. But I am in Canada.
I am aware of Voicestick’s i2Bridge service, but it is not provided in Canada and is not flexible enough. I am also aware of Pbxes.org services, but am note sure if they provide the flexibility of option (2)