The number of lines you have determines the number of concurrent calls may be placed across your company, as well as the total number of seats (phones) that may be installed. Each line can support up to five seats. You can always add more lines and seats as you go (and grow!).
Each seat allows one phone to be installed on your system. Typically, one seat is added per employee and for each additional phone within the company. You may add up to five seats per line. Each seat includes a free Cisco IP Phone rental with a term agreement of 36 months or more.