DECT hardware for linux

Greetings- I've been banging my head against a wall today trying to identify hardware and a source of supply. What I'm trying to do is implement a an Asterisk solution that uses DECT headsets. The headset endpoints have no requirement to dial out, only to participate in a conference bridge. I haven't been able to identify a DECT interface that will allow this. I'd also entertain a SIP-DECT interface that would be SIP to the asterisk box. Range for this solution needs to be about 40-50m. Does anyone have any suggestions or thoughts?