Shawn,
I have the DLink DVX (base) and DVG (ATA) units along with Aastra (all 3 models) and Dlink phones. The Aastra phones work fine for us and I have assigned, in some cases, 2 lines without issue...had no reason to try and assign more. Am running with switches that support POE along with UPS. We have not had a problem with the Dlink phones, but prefer the look and features of the Aastra as we keep the network and phone system up for awhile in the event of a power outage. Dlink did not have a phone with the POE feature and the styling was not well received. The folks were not fond of the silver color, the small display and the futuristic (
??) looks. They wanted a more traditional office looking phone whose layout and style was more in-line with what they had before. Nevertheless, I am still using them in locations where I only need basic phone service (public phone in waiting area, etc.) and POE is not an issue.
Be advised that the Aastra phones do seem to have a lot of programmable features (keys) depending on model, but I am not certain if they are all truly programmable for a RP system. If not mistaken, the Aastra RP phones are an off-shoot of their normal phones; just have the blue RP button and function added. In any event, the buttons are there and some do nothing out of the box, but because they are there, people are starting to ask about what they might be able to do with them. I have been so busy that I really have not had time to explore.