B737 FLC HAS ALTDEV DURING ARR TO PHX.

Narrative

WHILE ON ARR TO PDX; I COPIED THE ATIS DOWN ON A NAPKIN WHILE THE CAPT WAS FLYING THE AIRPLANE. WE HAD CLRNC TO CROSS BONVL AT 14000 FT. AS WE DSNDED TO 14000 FT AND LEVELED OFF; WE WERE SWITCHED OVER TO PDX APCH. I CHKED IN; STATING THAT WE WERE AT 14000 FT AND HAD RECEIVED THE CURRENT ATIS INFO. APCH RESPONDED WITH 'CONFIRM; YOU ARE LEVEL AT 13000 FT?' WE BOTH LOOKED AT OUR ALTIMETERS AND THE STANDBY ALTIMETER; CHKED THE SETTING AS WRITTEN DOWN ON THE NAPKIN AS 30.35 AND RESPONDED WITH 'NO; WE ARE LEVEL 14000 FT; WE'VE GOT 3 ALTIMETERS SHOWING 14000 FT.' 'APCH CONFIRM 29.35?' THAT'S WHEN WE REALIZED THAT I HAD COPIED THE WRONG ALTIMETER SETTING ON THE NAPKIN. WE CORRECTED THE SETTING TO 29.35 AND SHOWED US LEVEL AT 13000 FT. I ASKED APCH IF HE WANTED US TO CLB BACK UP TO 14000 FT AND HE RESPONDED WITH 'NO; THAT'S ALRIGHT; NO PROB; DSND TO 10000 FT.' WE CONTINUED OUR FLT TO PDX ON RADAR VECTORS AND DSNDING TO 4000 FT; THE CAPT ASKED THE CTLR IF EVERYTHING WAS OK AND IF WE NEEDED TO CALL A NUMBER. APCH CTLR TOLD US THAT WAS NOT NECESSARY. WE CONCLUDED OUR FLT WITHOUT INCIDENT. I THINK THIS ERROR COULD BE PREVENTED BY HAVING ACARS INSTALLED IN OUR ACFT; SO THAT WE HAVE WRITTEN PROOF OF THE ATIS RIGHT IN FRONT OF US. I BELIEVE I MADE THIS MISTAKE BY NOT LISTENING CAREFULLY ENOUGH; WHICH MIGHT BE IMPAIRED BY STATIC ON THE RADIO.