Upvote:1
Specific to The Philippines, and the referenced article, you will find Immigration offices right in the arrivals terminal(s). The visa is not activated or effective until you arrive and present yourself for entry into the country, through an international arrivals hall or section of the airport. In some countries, eligible nationals can receive a visa on arrival, a process that takes place prior to, or during, presenting credentials (passport, visa) and seeking permission to enter.
Some countries allow current visa holders to request permission to extend their stay, usually by visiting the offices of the appropriate authorities (e.g., immigration, foreigners). You would need your passport, the current (unexpired) visa, pictures, fee, and any other documentation required (e.g., application form, accommodation verification, copies of passport pages, etc.)