Is is necessary to have a wall phone jack for wifi?

[Richard]

You need to identify the Internet Service Provider you will use. This could be by satellite, but this can prove expensive. The most popular ISP connection is ADSL, which is carried over a normal telephone line. The line carries both phone and Internet signals.

The ISP connection comes into your place and connects to a modem/router. If you want to use a WiFi connection between the router and your computer, then the two should probably be less than 10 metres apart inside a building. With thick walls, then the distance could be much less for a reliable connection.

If the router is in the same room as the computer, then connecting the two by Ethernet is normally a better solution.

I hope this helps.