For one time advertising promotions or typical requests it is easier to use services of the outsourced call center. Main advantage of such a service is that the company who rents it is free from the necessity of keeping the operators and organizing their work flow.
VoIPCall is a Minneapolis based Internet Telephony Service Provider [ITSP] that provides a first class Voice Over IP calling service designed for business customers, Telcos, ISPs and government entities around the world.