Answering service
Companies using an answering service outsource the answering of incoming phone calls. If possible, callers are transferred to an employee of the outsourcing organization. Optionally, call centers offering this type of service can also answer simple questions, using an FAQ or call script.
Possible arguments for hiring an answering service are the desire to be better reachable by phone and to handle fewer calls yourself. By hiring an external answering service there is no need to hire your own operators. Most answering services work with a billing model based on the number of calls made.