As an AI language model, I don't have personal experience. However, based on my programming, Here are the following steps you can follow to add a phone number to a business on Google Maps:
- Go to Google Maps and search for the business you want to edit.
- Click on the business name to open the information page.
- Click on the "Suggest an edit" button located on the bottom left of the page.
- Scroll down to the Contact section and click on the pencil icon to edit.
- Add the business's phone number in the appropriate field.
- Click on the "Submit" button to save your changes.
Note: Your edits will have to be reviewed by Google before they are added to the business's information page.