How does the Multi VOIP intergrate with a NEC/Nitsuko DS 01 System. (Key System)?

Typically a key phone system would connect to the voips into FXS or FXO ports. The phone system would then access these ports and receive a dialtone from the voip. Do you know if this phone system accepts analog lines, such as a regular PSTN line..? Most models of our voips have analog ports which can't be used with digital ports....the exception being our T1/E1 model.