Question about 4 digit access code | Technical service details | Consumer forum

I activated a new phone just now and it asked me to make a 4 digit access code and gave me a new phone number etc...no problem here..my question is I have another SO phone which I bought 3 years ago when the phone number was already assigned and printed on the instruction inside the box, I don't remember I had to make up a 4 digit acess code and I don't think they asked me for the access code when I fill up this phone or ask for a referal code.

Anyone remember if that was the case, no access code for older phone? What is the access code for anyway? tia