I was recently at Polycom London for Lync 2013 Ignite training and had the pleasure of meeting a couple of Lync MVPs. Adam Jacobs (imaucblog.com) and Justin Morris (www.justin-morris.net). Both did presentations.
I had a chat with Adam Jacobs regarding hold music for the Aries phones and he indicated something was coming. A week ago he blogged about it.
Music on Hold and Cumulative Update Package (CU7) for Lync Phone Edition: December 2012
Justin Morris also blogged about it. http://www.justin-morris.net/december-2012-updates-released-for-lync-phone-edition/
I'm sure you'll all be reading the article, but long story short, Aries phones now have embedded Music On Hold! Long time coming and one off my list of missing features. Keep in mind that the hold music is embedded in the phone firmware and is not configurable. However I've had a listen to the Music on Hold file and it isn't bad. It plays the DefaultHold.wma file. Listen Here.
And yes I know that posting a link to another blog in a blog is cheating. But hey, how can I hope to say it better than the MVPs?
It does more than just Music On Hold as well. Description of the cumulative update for Lync Phone Edition for Polycom CX500, Polycom CX600, and Polycom CX3000 telephones: December 2012