There is no standard for rs232 over rj11 or rj45 (8 pins.)
standards that are convenient at the jack tend to result in inappropriate
pairing of signals in building wiring (there ARE standards for which
rj11/rj45 pins go in which pairs...)

cisco uses something like DSR CTS RD GND GND TX RTS DTR which has the useful
property (?) of changing DTE/DCE-ness when you flip the cable over, and of
allowing "smaller" cables to achieve smaller functionality.  (I might have
DSR/CTS and RTS/DTR reversed.)  Customers have complained about the
resulting pairing, though.  (we shamelessly copied the center 6 pins from
a common DEC terminal server scheme, just before they changed it, I think.)

BillW