Sip Trunks 

SIP is experiencing this surge in popularity as more businesses are migrating to next generation IP environments with wired and wireless networks. Try this site http://www.tierzero.com/what-we-do/business-voice/ for more information on sip trunks. More businesses are moving away from inflexible legacy telephone networks and are embracing SIP trunks, which offer reduced costs, improved productivity, centralization, disaster recovery and a first step to a full unified communications platform.
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