What is the difference between the DP01 and the DP01s?Updated 2 months ago

The DP01 is the main unit, which means it comes with a base station that connects to a phone socket and power source; it functions as the master unit and can connect up to 5 additional handsets. The DP01s comes without a base station and can be used as an additional unit; it doesn't require a phone socket but cannot operate unless linked to a base unit. 
The DP01s is not available for sale in the US. Customers in the US can purchase an additional DP01 main unit and pair it with another main unit. (up to six DP01 can be linked together and operate via one landline connection. 

For more info: https://www.punkt.ch/en/products/dp01-cordless-phone/#specs