Area code 301 (Maryland).

It's likely this board was 301, but the sysop Fanfan moved and took the board down. It briefly reappeared in 1994 as a Pentagram member board with a 202 (District of Columbia) area code. Both 301 and 202 are next door.

Jan 1994, PTG.NFO:

Digital Underground . │ 301-PRI-VATE │ Dr. Insanity. │ 3 │ MEMBER BOARD
The Kraal ........... │ 202-PRI-VATE │ Fanfan ...... │ 3 | MEMBER BOARD

A Feb 1994 PTG.NFO announces a new WHQ and it looks like the two boards merged hardware.

Digital Underground.. │ ITS-PRI-VATE │ Dr.I/Fanfan . │ 6 │ WORLD.... HQ