A virtual private network (VPN) is a network that uses primarily public telecommunication infrastructure, such as the Internet, to provide remote offices or traveling users access to a central organizational network. wikipedia.org

Juniper Networks designs and sells high-performance Internet Protocol network products and services. Juniper's main products include T-series, M-series, E-series, MX-series, and J-series families of routers, EX-series Ethernet switches and SRX-series security products. wikipedia.org

The Ultimate Security Package: Essential next-gen firewall protection for your network, web, email, applications, and users.

Cisco Systems, Inc. is an American multinational corporation that designs, manufactures, and sells networking equipment. It has a full range of router products from small business to enterprise solutions, typically using its own Cisco IOS operating system. wikipedia.org

Active Directory (AD) is a directory service created by Microsoft for Windows domain networks. wikipedia.org

Cisco ASA 5500 Series Adaptive Security Appliances, or simply Cisco ASA 5500 Series, is Cisco's line of network security devices introduced in 2005. wikipedia.org

Cisco Unified Communications Manager (CUCM), formerly Cisco Unified CallManager and Cisco CallManager (CCM), is a software-based call-processing system developed by Cisco Systems. wikipedia.org

Asterisk is a software implementation of a telephone private branch exchange (PBX). It allows attached telephones to make calls to one another, and to connect to other telephone services including the public switched telephone network (PSTN) and Voice over Internet Protocol (VoIP) services. wikipedia.org

Voice over IP (VoIP, abbreviation of voice over Internet Protocol) commonly refers to the communication protocols, technologies, methodologies, and transmission techniques involved in the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. wikipedia.org