They used to be made by Sipura - so guessing it comes from that.
From what I understand, a load of disgruntled engineers who made the Cisco ATA186 etc left Cisco to found Sipura, who released various ATAs and then later - phones. Sipura was purchased by Linksys and the SPA range moved to them (SPA9xx etc). Cisco then bought Linksys and launched the small business range, the SPA5xx which is largely the same as the SPA9xx series - but there is Skinny, XML browsers, better screens/tweaked hardware etc.
Some of that is rumour and hearsay - but I think it's roughly right!..
Steve
