I am unable to add a new standard Channel as the 'New' button is grayed out.
All Versions / Standard Channels
The standard product functionality does not allow the option to add or delete the standard channels in reference to which incidents are created and responded to. There is not a workaround available for this. However, you are able to edit a channel name that suits your business requirements.
Please note that the admin areas labeled as Channel Types (located within Customizable Menus), Channels and Channel Accounts do contain additional options related to Social Media (e.g. YouTube, Twitter, Facebook). These channels are no longer used within the product as the Social Monitor feature was deprecated August 2017. Removal of these is planned for a future date.