Ricoh Aficio MP 161SPF - Manual (Page 178)

Registering Addresses and Users for Facsimile/Scanner Functions
170
7
C
Select [Register as] using {U} or {T}, and then press the {OK} key.
D
Select [Sender Only] using {U} or {T}, and then press the {OK} key.
E
Press the {Escape} key.
F
Press [End].
G
Press the {OK} key.
Reference
p.147 “Registering a User Code”
Changing a fax number
A
Enter the new fax number using the number keys, and then press the {OK} key.