These phones are designed to work really well with just a cellphone. I do not have a landline at all and one of my favourite features is that you can disable it entirely (otherwise the handsets will display a message that your landline is experiencing problems).
The built in phone book easily populated itself through bluetooth with the contact list on my cellphone. Despite the warning in the instructions that there may be issues with importing contacts with pictures attached to their listing, all of my numbers were imported without any problems.
The phones also correctly receive caller id information from my cellphone and I like that they also say the name of the caller when the phones are ringing.
I have not tried the feature that allows the handsets to ring using the cellphone's ringtone so I cannot speak to that.
Otherwise, pairing was easy, the range on connection is good, and voice quality is on par with my cell.