Caller ID states it's WGBH (Boston public TV and radio), which seems plausible.
They've been calling relentlessly for weeks from this and other numbers despite my call blocker feeding them disconnect tones, fax machine noises, etc.
Other numbers they call from (for your pre-emptive call-blocking pleasure):
617-274-0732 http://800notes.com/Phone.aspx/1-617-274-0732
617-274-0738 http://800notes.com/Phone.aspx/1-617-274-0738