With some lateral thinking and reading #eventphone tech info + some #ETSI docs, (HT to #CCC 🎩 😎) I was able to heck the Ascom IP-DECT base station at the larger site I work at into letting me register my Gigaset Pro DECT (€90) instead of the proprietary Ascom handsets (€200!)
ofc its basic GAP, I don't get the messaging features and roaming across the multiple base stations isn't as seamless, but it does work as a telephone (useful as LTE signal is non existent on the lower ground floor)
link is below (apologies for long text that assumes a bit of basic knowledge of DECT and lack of screenshots, but I'd have to redact so many things because its a live system in use at my work).
Hopefully should be understandable to anyone who has set up a Fritzbox or similar (although I'd be impressed if anyone manages to get Ascom kit for hackspace etc as its usually +€€€)
HT to @er1n for her excellent md.hecke.rs site 🎩 😎
@vfrmedia nice. Writeup?