The relationship between a Call channel and a Call.Content object is somewhat comparable to the relationship between Connection and Channel.  

- Channels are created with a method on Connection (e.g. CreateChannel(), etc.).  Call.Content objects are created by a method on Call (AddContent()).
- Channels are closed by a method on itself (Close()), Call.Content objects are removed by a method on itself (Remove())
- Changes in the existing Channel objects are communicated by signals on the Connection Object (NewChannels, ChannelClosed).  Changes in Call.Content objects are communicated with signals on the Call object (ContentAdded, ContentRemoved)

The one difference between this analogy is that the Channel object itself also has a 'Closed' signal, but the Call.Content object does not have a 'Removed' signal.  If this were added, I think it would improve the API consistency.