No there is no softphone as yet, you can use office link instead, There is extra port forearding required for Chat, check the engineering guidelines.
I just went through the Engineering Guide, as the chat is something we've been looking for as well. They don't list chat as a feature of the iOS software products, but do for Blackberry and Android.
I know you can do chat via UCA 5.X webpage, so that might be an option for the iOS products.
I know from the people in our office with Androids, the chat feature causes problems on their phones (freezes) and drains their battery pretty good, so that's maybe by iOS doesn't have that yet. Don't know for sure, just a thought.