B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 453
Communication Breakdown; Confusion; Situational Awareness
Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Incursion Taxiway
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance
Procedure; Human Factors; Airport; Chart Or Publication
Metering was in effect. Metering pushed us to Ground for pushback clearance. Ground cleared us to push back at our discretion. Captain gave the ground crew clearance to push us back. The Captain initially told me to just start one engine. Once he noticed the ground crew was turning our tail north; he told me to go ahead and start both engines due to the position we would be in (parallel to Runway XX/XY facing southeast). Ground Control called shortly after we came to a stop advising us to call the Tower and relayed a phone number. Ground also informed us to call our Operations. The Captain and I elected to make the call to the Tower prior to our departure; and coordinated with Ground for a spot to taxi to and hold. The phone call to Tower made us aware that we were pushed onto [a] Taxiway without specific clearance to do so. Our [Company procedures] only addresses [certain] gates when it comes to specifically requesting pushback clearance onto [the] Taxiway.Our procedures need to be updated to include [this gate] with the other highlighted gates. Our ground crews should be informed that pushback from this gate should be into the alley unless told otherwise by the crew. Ground (like most airports) should be specific with push instructions (i.e. push into the alley; push onto [Taxiway]; etc.).
B737-800 First Officer reported they pushed back onto a taxiway without clearance from Ground Control.