This needs no add-on, no extension and no account, and it is the right answer for a short list. Five minutes end to end.
Step 1. Get the numbers into a callable format. Store each number as digits with the country code and nothing else: +919876543210, not +91 98765-43210. Spaces, dashes and brackets are the single most common reason a tel: link does nothing when tapped. If your column came from an export and has formatting in it, clean it with =SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A2," ",""),"-",""),"(","") or simply Find and replace across the column. Also watch for Sheets stripping a leading zero or converting a long number to scientific notation: format the column as Plain text (Format, then Number, then Plain text) before pasting.
Step 2a. One number, by hand. Click the cell, press Ctrl+K (Cmd+K on a Mac), and enter tel:+919876543210 as the link target. Ctrl+K is simply the insert-link shortcut in Google Sheets; there is nothing calling-specific about it. The tel: prefix is what tells a device to hand the number to its dialer rather than treating it as a web address.
Step 2b. A whole column, with a formula. In an empty cell beside the first number enter =HYPERLINK("tel:"&A2, A2), then drag the fill handle down the column. Replace A2 with whichever cell holds your number. Every row now shows a tappable version. If you would rather see the person’s name than the digits, use =HYPERLINK("tel:"&B2, A2) with names in A and numbers in B.
Step 3. Open it on a phone, not a desktop. This is the step people skip and then conclude the method is broken. A tel: link on a desktop does nothing unless a softphone is installed and registered to handle it. Open the sheet in the Google Sheets app on Android, tap the link, and the dialer opens with the number filled in. You still press the green button; a tel: link never places a call by itself.
Step 4. Share it correctly. If colleagues will call from the same sheet, share with at least Viewer access. The links work for anyone who can open the file. Note what this does not give you: two people tapping the same sheet have no way of knowing the other already rang that number, which is the first thing that breaks once more than one person is calling.