Format phone User Field display value in the member directory.

my_pmpromd_phone_display_value.php

<?php
/**
 * Format phone User Field display value in the member directory.
 *
 * Replace cell_phone on line 14 with your phone field's field name/meta key if different. 
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
function my_pmpromd_phone_display_value( $value, $element, $pu, $displayed_levels ) {

	if ( 'cell_phone' === $element ) {
		// Get the raw value directly from user metadata.
		$raw_value = get_user_meta( $pu->ID, $element, true );

		// If no value is found, return the original value.
		if ( empty( $raw_value ) ) {
			return $value;
		}

		// Format the phone number.
		$value = formatPhone( $raw_value );
	}

	return $value;
}
add_filter( 'pmpromd_get_display_value', 'my_pmpromd_phone_display_value', 10, 4 );