Enter phone in the "Search the archives" box at https://en.wikipedia.org/wiki/Wikipedia:Reference_desk
It gives this search:
https://en.wikipedia.org/wiki/Special:Search?fulltext=Search+the+archives&fulltext=Search&prefix=Wikipedia%3AReference+desk%2FArchives&search=phone&ns0=1

Two hits on the first page are currently to section headings ending in a space followed by a question mark " ?".
Both hits display the section heading in red and make an apparent redlink to the full page instead of a blue link to the section on the page. For example, there is a hit saying:
Wikipedia:Reference desk/Archives/Miscellaneous/2018 November 6 (section Where is this phone number ?)

"Where is this phone number ?" links to:
https://en.wikipedia.org/w/index.php?title=Wikipedia:Reference_desk/Archives/Miscellaneous/2018_November_6&action=edit&redlink=1

The page does exist so the link redirects to:
https://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Miscellaneous/2018_November_6

The link in the search hit should have been blue and included the heading:
https://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Miscellaneous/2018_November_6#Where_is_this_phone_number_%3F

If a section heading ends in a question mark without a space before it then there is no problem, for example:
Wikipedia:Reference desk/Archives/Computing/2016 January 18 (section Does having a phone service reduce available ADSL bandwidth?)

"Does having a phone service reduce available ADSL bandwidth?" links correctly to:
https://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Computing/2016_January_18#Does_having_a_phone_service_reduce_available_ADSL_bandwidth%3F