Landlines are based on excellent but century-old technology, which AT&T has gotten permission from the state to stop supporting. Many small businesses have a mysterious box of equipment in a phone closet that nobody knows anything about, a box with a mess of connections to AT&T that nobody knows anything about. Expanding, moving, or almost any configuration change can be a challenge.
Internet-based telephony, called “VoIP” for Voice over IP (IP being the language of raw bytes travelling the Internet) is mature and ready for businesses of all sizes. “Fully hosted” VoIP requires no special on-site equipment, only telephones connected to a local network over the same type of wiring that connects computers. The local network must be properly configured to support VoIP, but once configured, it just works. Move or add a desk? Just plug in the phone like a computer. Move to a new location? Set up the local network correctly in its new location and plug phones in just like computers.
It might be time to make a move to excellent and in most cases less costly VoIP.