It seems that the issues that are reported in other comments have been fixed :
- the country and zoiper icons can be disabled (there is an option for each icon)
- only numbers that 'look like' phone numbers are taken into account
- I didn't get any http error
- you can disable the plugin for a page / an entire website

The only point that might be enhanced : it would be nice to have on option in order to take into account only tel: hyperlinks

Great add-on, does whatever it is supposed to!