Use the Telephone field to collect people’s phone numbers, complete with the country code.

The Telephone field displays +44 as the default phone code, which can be changed as per your need
The complete contact number is now saved under the contact profile.

How the Telephone field appears in a form

A flag appears and a Country Code
Anyone filling in the form with this field can click the Flag to display a dropdown list containing other country flags and their country code

How to create a Telephone field

Click Create in the top menu
Select More Options
Select Contact Form
You arrive on that Custom Form’s Manage Fields page
Give it a name
From here you can click Create a Field or question to create a new field
There is a filter called Telephone Number which lets you filter to see the fields of the Telephone type.
Once you have selected the Telephone-Type Field, it appears on the right
You can press the Remove button to remove it or the arrows to change the order of the fields.

To enhance user experience on Makerble's web app accessed via mobile phones, the Telephone Number field is hyperlinked.

Moreover, phone numbers are hyperlinked on desktops.

However, unless the user is using applications like Skype, the hyperlink may not have any effect.

Click My Apps in the top menu
Click Contacts app
Select the contact that you need to make a call
You arrive on Contact Profile page of the specific contact.
Scroll down. On the left side you can find the contact number.
Click the contact number.
When you click on it, it initiates a call on your phone
On desktop, it will create a popup message: asking to select the app that will make a call on desktop.
Selecting the app will take you the app where you can proceed the call