About This HTML Issue
A tel: URI in an href attribute must not contain spaces. The phone number should be written as a continuous string of digits, optionally prefixed with + for the country code.
The tel: URI scheme is defined in RFC 3966. It allows digits, hyphens, dots, and parentheses as visual separators, but spaces are not permitted. Browsers may still dial the number if spaces are present, but the markup is technically invalid.
A common approach is to use the full international number with no spaces in the href value while keeping a human-readable format in the visible link text. If you want visual separators in the href, use hyphens or dots instead of spaces.
Invalid example
<a href="tel:+1 555 123 4567">Call us</a>
Valid examples
<a href="tel:+15551234567">+1 555 123 4567</a>
<a href="tel:+1-555-123-4567">+1 555 123 4567</a>
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