I am not able to click on telephone number hyperlink sent on Gmail app in iPhone.

Try to check with other hyperlinks but phone number hyperlink is not working. Below is example.

<a href='tel: 911234567890' target="_blank">1234567890</a>

CodePudding user response：

Apparently, this problem appeared in 2020 and has still not been solved: https://support.google.com/accounts/thread/39339110/phone-number-is-no-longer-a-clickable-link-in-emails-on-gmail-for-ios?hl=en.

I think the technology behind this feature is patented by Apple, that's why it doesn't work for Gmail.