CAPT OF AN MLG TAXIED INTO POS ON THE RWY WITHOUT TWR INSTRUCTIONS.

Narrative

WHILE AWAITING DEP CLRNC AT RWY 26R AT PHX; I TAXIED MY ACFT PAST A CESSNA 182 ALSO AWAITING DEP CLRNC. THE TXWY AND PAD AT THE END OF RWY 26R WILL ALLOW 2 ACFT TO HOLD SHORT OF THE RWY WHILE NEITHER IS BLOCKED BY THE OTHER. THE LCL CTLR WILL SOMETIMES CLR 2 AIRPLANES INTO POS IN TANDEM; REQUIRING THE SECOND TO 'MAINTAIN VISUAL' WITH THE FIRST; WITHHOLDING TKOF CLRNC FROM THE SECOND ACFT UNTIL THE FIRST IS AIRBORNE AND SEPARATION IS ATTAINED. I WAS ANTICIPATING THIS COULD OCCUR. AS I WAS CONCENTRATING ON POSITIONING MY ACFT; MY FO READ BACK 'POS AND HOLD (FLT IDENT).' HEARING THIS; UNCHALLENGED BY TWR; I TAXIED INTO POS BEHIND THE CESSNA. THE CESSNA RECEIVED TKOF CLRNC AND DID SO IMMEDIATELY FOLLOWED BY A CLRING TURN AWAY. THIS ACTION FURTHER REINFORCED MY PERCEPTION THAT WE HAD BUT A FEW SECONDS WAIT PRIOR TO BEING CLRED FOR TKOF. HAVING WAITED APPROX 30 SECONDS WITHOUT RECEIVING TKOF CLRNC; AND BEING AWARE OF CLOSE-IN ARR TFC; I XMITTED THAT WE HAD 'VISUAL ON THE CESSNA' TO PROMPT THE CTLR THAT WE NEEDED TKOF CLRNC. HE REPLIED THAT WE HAD NOT BEEN CLRED ONTO THE RWY AND SHOULD EXIT IMMEDIATELY. WE DID SO. THE ARRIVING ACFT WAS ABLE TO LAND WITHOUT DELAY OR EVASIVE ACTION BEING REQUIRED. THE KEY IN THIS SIT WAS MAINTAINING SITUATIONAL AWARENESS AND ALLOWING FOR A MISSED COM. AS LONG AS WE ARE DEPENDENT ON VERBAL COM; WITH SEVERAL PARTIES ON THE SAME RADIO FREQ; THESE SITS WILL REOCCUR.