Ty @rsn for nudging me in correct direction
https://newbedev.com/can-t-change-tel-protocol-handler-in-windows-10
did it
Edit: something like this
writeReg("HKEY_CURRENT_USER\SOFTWARE\Classes\callto", "", "URL:callto")
writeReg("HKEY_CURRENT_USER\SOFTWARE\Classes\callto", "URL Protocol", "")
writeReg("HKEY_CURRENT_USER\SOFTWARE\Classes\tel", "", "URL:tel")
writeReg("HKEY_CURRENT_USER\SOFTWARE\Classes\tel", "URL Protocol", "")
writeReg("HKEY_CURRENT_USER\SOFTWARE\Classes\dialer.callto\Shell\Open\Command", "", '"' & @ScriptDir & '\' & $appName & '.exe" "%1" /phone')
writeReg("HKEY_CURRENT_USER\SOFTWARE\Dialer\Capabilities", "ApplicationDescription", "Dialer")
writeReg("HKEY_CURRENT_USER\SOFTWARE\Dialer\Capabilities", "ApplicationName", "Dialer")
writeReg("HKEY_CURRENT_USER\SOFTWARE\Dialer\Capabilities\URLAssociations", "callto", "dialer.callto")
writeReg("HKEY_CURRENT_USER\SOFTWARE\Dialer\Capabilities\URLAssociations", "tel", "dialer.callto")
writeReg("HKEY_CURRENT_USER\SOFTWARE\RegisteredApplications", "Dialer", "Software\Dialer\Capabilities")
Func writeReg($p, $n, $v)
If @error Or RegRead($p, $n) <> $v Then RegWrite($p, $n, "REG_SZ", $v)
EndFunc ;==>writeReg