In the hospitality and education sectors, on-premise phone systems are still widely utilized despite the growing adoption of hosted VoIP systems. These systems rely on either a 23-channel PRI (Primary Rate Interface) or SIP Trunking for service delivery. A PRI allows up to 23 simultaneous calls, and if more capacity is needed, additional PRIs must be added. Alternatively, some systems use SIP Trunking, which facilitates communication over the internet, enabling voice, video, and instant messaging exchanges in milliseconds with reliable call quality. Unlike PRIs, SIP Trunking offers flexibility, allowing organizations to scale their active lines up or down based on their specific needs. While these legacy technologies are being gradually replaced in many industries, they remain a practical and functional solution in schools and hospitality environments where they continue to meet operational demands effectively.