They’re available dirt-cheap at the moment, thinking of grabbing a few.
Yes, the S450 is very good. I picked up a pack including the base station and six handsets for fifty quid, delivered. Have a poke around on eBay, there seem to be quite a few bits of refurb kit going cheap at the moment. In fact, only the base-unit box had even been opened, the other 5 handset’s boxes were still factory-sealed.
Setup is a doddle, within minutes I had it talking to both my landline and my Asterisk box. Note that Asterisk treats the entire system as one extension, although I’m not entirely sure some cleverness can’t be applied.
The dual-phone functionality is a bit of a waste to be honest, as my POTS line will shortly be connected to Asterisk anyhow, and all phones in the house will run over Asterisk. But at this price-point, it beats the pants off any wireless IP phone on the market (at least for domestic use), and I still have the option of connecting direct to the landline if I ever need to. Like, for example, when I fiddle with Asterisk and break it