A static IPv4 address stays the same across reconnects. On Broadbent Network it is included with symmetrical full fibre, and it is applied once the line is live.
Which products include one
Symmetrical full fibre includes a free static IPv4 address. That is the product where download and upload are the same speed.
Other broadband products use a dynamic address unless you ask for a static IP.
When it is assigned
The address is assigned after the circuit is live. It is not chosen at checkout, and a particular number is not reserved before the network marks the line live.
The same address is not guaranteed if the service is later migrated or provisioned again.