This is a single DP720 portable DECT 6.0 phone that is meant to be used with (requires) a DP750 IP Base Station. Buy this if you already purchased the DP720+DP750 bundle and need to add handsets (up to a totasl of FIVE). This is a great entry level cordless solution.
 
This is a very good lower cost wireless solution.
additional handsets for the base station are inexpensive.
 
However if you have a larger location with good wifi the WP820 cordless may be a better option.