asterisk::iax should have a list of params like asterisk::sip instead of $contents

[lelutin]

To make the resource more friendly and manifests using it more self-describing, the asterisk::iax defined type should enumerate parameters that are valid values for iax contexts. we'd also need to change the template for iax snippets

[lelutin]

If I understand correctly that documentation, channel definitions can override general options + have channel-specific options (from Channel-specific parameters section):

http://asteriskdocs.org/en/2nd_Edition/asterisk-book-html-chunk/asterisk-APP-A-SECT-1.html