Answer by systempuntoout for Can I make a phone call from HTML on Android?

Yes you can; it works on Android too:

tel: phone_number
Calls the enteredphone number. Valid telephone numbersas defined in the IETF RFC 3966 areaccepted. Valid examples include thefollowing:

* tel:2125551212* tel: (212) 555 1212

The Android browser uses the Phone app to handle the “tel” scheme, as defined by RFC 3966.
Clicking a link like:

<a href="tel:2125551212">2125551212</a>

on Android will bring up the Phone app and pre-enter the digits for 2125551212 without autodialing.

Have a look to RFC3966