Before my upgrade to Adobe Acrobat DC on my iPhone, telephone numbers in a excel spread sheet was recognized by Acrobat Reader as such i.e. You would touch and hold the number, then a 'pop up' would appear that gave the option to 'CALL' or 'SEND A MESSAGE'. This function no longer works in Adobe Acrobat DC, why not?
Acrobat DC for iOS uses the Apple iOS SDK to display the preview of non-PDF documents (e.g. Word, Excel, PowerPoint).
It looks like an Apple bug for failing to auto-detect phone numbers only in Excel spreadsheets.
I opened my Excel (.xlsx and .xls), Word (.docx), PowerPoint (.pptx) documents with phone numbers in Acrobat DC for iOS. The phone numbers in the Word and PowerPoint documents were correctly recognized as such. In the preview, the plain text turns into blue underlined text. When you press and hold over the phone number, you will get the options that you have mentioned.
On the other hand, the phone numbers in the Excel spreadsheet were not recognized in the preview. In Excel, I used Format Cells > Number > Special > Phone Number with United States (English) as language. But it did not fix the problem.
As it turns out, the Apple Mail preview (on iOS 8) has the same problem. You can also email your Excel spreadsheet to yourself and open it in Apple Mail on your iPhone to confirm that it is an Apple bug.
You may want to post a question in the Apple Support
or use Word documents instead for auto-detection of phone numbers.
Sorry for the inconvenience.