Is this just OpenAnswer repackaged?

No, although it is based on and modelled after OpenAnswer – SwitchBoard TAS was written from the ground up and made similar OA to ease training.

Can I keep / use my existing DIDs/ Voip Provider? 

In most cases yes.  As long as you are able to deliver to a SIP URI you should be able to keep your current provider.  

Are there any other fees per month besides the cost of seats? 

No, you only pay for the seat rental and telco costs.

Is there a failover/ emergency backup? 

Yes, in the event you are disconnected or have no operators available calls can be rerouted to our call, another center of your choice or pretty much any number you like.

What message delivery options are available? 

All standard methods are currently available, Email, Fax and SMS Text.  Currently we are developing SMS with reply, where your clients can txt reply message receipt.