When utilizing Click2Call inside Google Docs or Sheets... Click2Call will fail when trying to dial from the doc or sheet. In order to work around this, you can use the following tool provided by ZoHo:

Go to this link: https://sheet.zoho.com/excelviewer

Once you are there, select the Choose Your File radio button-> Click in the box below-> Select the Excel file that has the numbers you want to dial. When it opens you will be able to use click to call to dial the numbers without it failing.