How to Install an older version of php using apt-get?

Question

I have this older package in this exact version that I want to install on Ubuntu.

https://launchpad.net/ubuntu/+source/php5/5.3.10-1ubuntu3.20

Answer 1

For those looking for an earlier version of php 7.

List all php 7 versions:

apt-cache policy php7.*

Specify and install a specific php 7 version, in example 7.4.3:

sudo apt install php7.4-fpm=7.4.3-4ubuntu2.2
                          ^ ^
                          | |
            (left) pkgname / (right) version part