Here's the obvious and straightforward way, which has the major disadvantage of silently not updating if the manager changes and perhaps making you call the wrong number at an inopportune time:

Jane's manager's phone number is {{ChrisSmith!!phone}}.

Now for trying to make it grab the manager's name from the manager field on the fly. You may have been tempted to try:

{{ {{!!manager}}!!phone }}

…but unfortunately this does not work.

There are actually two separate reasons it doesn't work. First, TiddlyWiki doesn't parse other wikitext within {{double curly braces}}, it only looks for a tiddler name/field. Second, even if it did, it would fail for the same reason that this didn't work in an exercise in Macros:

<<wikipediaLink>>Aardvark

If you need a refresher, TiddlyWiki processes the contents of transclusions (of variables and macros, as we saw before, as well as of fields) separately from the surrounding content, so the result of {{!!manager}} (namely, ChrisSmith) is an entirely separate piece of wikitext to TiddlyWiki. Thus, what it would see would be three separate, unconnected pieces: {{, ChrisSmith, and !!phone }}.

Here's a method that works and uses only tools we've already seen. If you worked at it long enough, you might have gotten this or something similar:

\define getPhone(person)
{{$person$!!phone}}
\end

Jane's manager's phone number is: <$macrocall $name="getPhone" person={{!!manager}} />

That said, understanding why this works when {{ {{!!manager}}!!phone }} doesn't is likely beyond your TiddlyWiki knowledge at this point, so don't feel too bad if you didn't get it. We'll see the explanation in Text Substitution.