How know local and STD number?
If you're talking about Sexually Transmitted Diseases, and
you're in the US, here is a local STD hotline for all states...and
it's toll-free, just call 1-877-889-5407.
If you're talking about Subscriber Trunk Dialing and asking
"what is the telephone number of this phone?" then the only general
advice I can give you is to first look to see if there is a label
on or near the telephone with the number, or otherwise call someone
who has Caller ID and ask them to read back to you the number you
called from.