You simply cannot do without VoIP for your business communications. However, Voice over Internet Protocol is a generic term covering the use of various underlying technologies, each with its specific plus points. Given just how extended one platform can be it is virtually impossible to find a single developer proficient in all such technologies like FreeSWITCH, Asterisk, WebRTC, OpenSIPS, and Kamailio. The best thing to do is to hire a VoIP Developer Company that employs specialists in each of these platforms. That way you get the benefit of individual and combined expertise for the implementation of gateways, IP PBX, SIP Serves, IVR, and contact center solutions as the case may be.