B737 FLC FAILS TO STOP AT HOLD LINE. GND CTLR INTERVENES.

Narrative

EL PASO INTL GND OPS: DIRECTED TO TAXI FROM GATE; WATCH FOR COMPANY COMING IN FROM RWY 22. CAPT UNDERSTOOD TO TAXI TO RWY 22 (BUT MIGHT HAVE REALLY BEEN RWY 26). CONFUSION DEVELOPED WHEN COMPANY CHATTER PARTIALLY COVERED UP GND XMISSION. CAPT READJUSTED VOLUME LEVEL DOWN ON COMPANY AND ACCIDENTALLY BUMPED VOLUME DOWN ON GND. APCHING RWY 8/26 CAUTIOUSLY; WE WERE DIRECTED TO HOLD SHORT. I DID NOT HEAR THAT XMISSION. GND NOTICED THAT OUR ACFT HAD SLOWED DOWN; BUT NOT STOPPED. GND YELLED 'STOP' LOUD ENOUGH ON THE RADIO THAT I HEARD THE INSTRUCTION AND STOPPED (WITH THE ACFT NOSE JUST PAST THE HOLD SHORT LINE). I REALIZED WHAT HAD HAPPENED AND READJUSTED VOLUME CTL. THANKS TO AN ALERT GND CREW WE DID NOT TAXI ONTO AN ACTIVE RWY. HOWEVER; I DID REEMPHASIZE TO MY FO THAT HE MUST ENSURE IMMEDIATE AND CORRECT CAPT COMPLIANCE TO TWR CTL OR TAKE CORRECTIVE ACTION. LESSONS: 1) ALWAYS REPEAT GND COMMANDS VOCALLY BTWN THE COCKPIT CREW; ENSURE AGREEMENT; 2) ALWAYS RECHK VOLUME CTLS CHANGES WITH SQUELCH BUTTON; AND 3) BRIEF COPLTS THAT GND TAXI ARE ALSO PART OF THEIR RESPONSIBILITIES.