We used to use Ruby Receptionists, back before we hired an assistant. They were great! They answer however YOU say, and work closely with you to make it all seamless. They even have ways to figure if this is a high-priority call (rules you set with them, and they asked some good questions) and can then transfer TO you if need be. Ruby (all the ladies are "Ruby") calls you and gives the basics, and up to you to decide if this is a real emergency to take. The pricing at that time was very reasonable, and we signed up for three months at a time, every year for a couple of years.
Ruby Receptionists