What is the proper schema for JSON-LD telephone number with extension?

Question

I'm trying to find the proper schema for telephones with extensions, but I can't find anything related to this problem through Google searches or schema.org.

In HTML, I'm using , to trigger the extension on cellphones and Skype, but I've also seen p used to "pause" between numbers when dialing. Which is the best route in regards to proper JSON-LD schema?

No extension used:

{
     "@type":           "Organization",
     "telephone":       "+18665554985"
}

Style 1 using p:

{
     "@type":           "Organization",
     "telephone":       "+18665554985p100"
}

Style 2 using ,:

{
     "@type":           "Organization",
     "telephone":       "+18665554985,100"
}

Answer 1

The telephone property has Text as expected value. If a specific format should be used, it would be noted in the property’s description, but that’s not the case for telephone.¹

So you can use whichever format you want.

Which format would make sense? I would go with the same format you display for your users (which would ideally be the recommended format according to a convention/standard relevant for the targeted users). This is the natural choice when using Microdata or RDFa to mark it up, and there is no reason to go a different route for JSON-LD. This would also help in cases where a consumer simply displays your value of the telephone property: it will be in the appropriate format for your users.

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¹ There was some discussion about this in the issue Make the telephone property more structured (not just Text). I would expect that the expected range will, at some point, include URL values, so that tel URIs can be used (which of course have a specified format).