I did not find the "glossy" ASP material on the OBi webpages sufficient; thus going to ASP (ITSP) web sites.
Actually, I already have an ITSP provider (Callcentric) with a free DID and probably continue as-is with them. Though a little pricey for pay-as-you-go, my needs are simple. Fortunately the PAYG are rollover, at least in one sense since there is no monthly subscription fee.
Time will tell.