I can walk you through adding more customer information in your estimates, cepi92.

When you create a sales transaction, we have the default Email field for the customer's email address. To add a Phone Number, you can add custom fields. Let me show you how:

1. Go to the Gear icon and click Custom form styles.
2. At the upper-right, click New style > Estimate.
3. Select the Content tab and click the header section of the sample template.
4. Scroll down to see the + Custom field option.
5. Check the box and enter a custom name something like Phone Number.
6. Click Done to save.

When you create an estimate you have the option to manually enter the Phone number. To give you more details about customising sales forms, you can check out this article: Customise invoices, quotes, and sales receipts in QuickBooks Online.

Feel free to post your questions here. Take care and wishing you all the best. Take care!