Several threads on the Ooma forum have lamented the lack of wildcard call filtering with Ooma Premier. This issue of needed wildcard call filtering is getting some good coverage in a Comcast forum http://forums.comcast.com/t5/Universal- ... d-p/797768 Folks with Comcast phone service are annoyed with the minimal call filtering capabilities they get - only 12 phone numbers can be blocked and no wildcards are allowed. Standalone call blockers such as the Digitone Call Blocker 10 http://www.digitone.com/ support wildcard call filtering. Because I have Comcast service concurrently with Ooma while I am considering a switch to Ooma and a Digitone I thought I would try the Digitone hardware behind the Ooma Telo hardware and see how it worked. My Ooma number doesn't get telemarketing calls yet so I had to test the system with my cell phone (area code 612) and my current landline phone (area code 763).
The conclusion from the test is that a Digitone behind a Telo works perfectly for explicit number and wildcard area code call blocking thus addressing that limitation with Ooma Premier. I recommend reading the Comcast thread for other commentary. Digitone Call Blocker 10 is currently $100 but seems well worth the upfront investment in hardware - it doesn't seem like the phone service providers are going to give us the call filtering capabilities that would be useful; if they wanted to do it they could have done it quickly and we have been asking for it for a while.
Note that the current model Digitone only allows wildcard block at the area code (e.g 877*) or more general (e.g. 8*) levels however a new model they expect to release this year will allow blocking at the exchange and more detailed levels (hence you could wildcard block the phone bank at your alma mater without blocking all your friends in the same town). Another system called Caller Id with Ring Controller http://www.jfteck.com/caller-id-with-ri ... roller.php appears to offer similar features as the Digitone but I haven't used one to be able to comment usefully on it based on experience.