Oh absolutely Greg, I wish I had thought of RTR. In digging though the past via Google it appears that Aastra was a model citizen corporation and was very friendly to Asterisk. I have 2 of their older phones and when I got 'em it was soon after the Mitel acquisition and the Aastra FTP server was still active and I got my firmware for them. Mitel wasted no time in shutting that down. Shoretel was a purchase of Mitel’s and I am quite sure it was done as a way to knock off a competitor and Mitel will quickly throw their products into development hell and start pitching the Mitel products to Shoretel customers as upgrades.
To be fair Mitel does pitch SIP phones - the 68xx series - but they are doing the same thing Cisco is doing and that is doing what they can to make it impossible for their “proprietary system IP phones” to interoperate with open systems. They know, of course, that many time large corps will wholesale dump hundreds if not thousands of phone sets onto the market when they “forklift upgrade” their phone systems and they do NOT want those phones diverted into use with other people’s phone systems (like FreePBX)
As for using Shoretel on Asterisk/FreeBSD you want this: