This from the manual (P=button above 1, S=speaker vol. bottom right, M=button above 2).
Memory
The telephone will store 13 numbers into memory (3 one-touch memories and 10 two-touch memories).
When a number is stored in memory, you need only press one or two buttons dependant on location to make a call. One-touch memories are numbered M1-M3, two-touch memories are stored using the telephone keypad digits 0-9.
Storing One-touch Memories
1. Lift the handset and press P (ignore anything you hear in the earpiece).
2. Enter the phone number to be stored (up to 24 digits).
3. Press P again.
4. Select a location M1-M3 by pressing the corresponding button.
5. Replace the handset. The number is now stored.
Dialling using One-touch Memories
1. Lift the handset (or press the S button) and wait for a dialling tone.
2. Dial the desired number by pressing the corresponding memory location (M1-M3).
Storing Two-touch Memories
1. Lift the handset and press P (ignore anything you hear in the earpiece).
2. Enter the phone number to be stored (up to 24 digits).
3. Press P again.
4. Select a memory location by pressing one of the keypad numbers 0-9.
5. Replace the handset. The number is now stored.
Dialling using Two-touch Memories
1. Lift the handset and press S (ignore anything you hear in the earpiece).
2. Press M.
3. Select the memory location where the number is stored by pressing the relevant keypad number 0-9.