Having ported my number several times, now, I have learned that each time you do so, you must reregister your number with the Federal Do Not Call list at www.donotcall.gov . Apparently, the act of porting removes your number from the DNC list and you will, in my experience, instantly start receiving telemarketer calls. Note that it takes 30 days or so after registering for it to take effect.

I'd like to suggest that Voipo add a note to their "welcome letter" pointing out this matter.