CWU is presently $0.0095/min. to US. For click-to-call, etc., you can usually have the originating leg go VoIP, so a PSTN call is not needed at all.
CWU does offer US DIDs, but you must order from a non-US IP address (because they don't offer 911). IMO, the cost (typically $4.50) is not unreasonable, given that you get several channels and 3000 minutes, with business use permitted, etc. You can also use e.g. a free Callcentric DID, forwarded to CWU by SIP URI.
For Belarus (and possibly Ukraine), you might give Voxbeam a try. You get a small credit at signup, so you can test without making a payment.