The addon will not detect all phone numbers. For example, it will not detect phone numbers in images, word-based phone numbers ('1-800-FLOWERS'), oddball formats ('1- 508- 555 - 1212'), and phone numbers split with an HTML tag ('508-<b>555-1212</b>' or '508-555-<wbr>1212'). I may add support for some of those in the future.
The addon currently only supports phone numbers from North America (ones with the country code '1'). If there appears to be enough demand for it, I will add support for phone numbers from other countries.
If you encounter any problems, please let me know, and I will do my best to take care of them.