Date: 201506
Local time of day: 1201-1800
Location: EWR.Airport, NJ
Flight conditions: VMC
Light: Daylight
Aircraft: Large Transport; Low Wing; 2 Turbojet Eng
Operator: Air Carrier
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ground EWR
Reporter organization: Air Carrier
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Confusion; Situational Awareness
Second reporter function: First Officer; Pilot Not Flying
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
Detector: Automation Air Traffic Control
When detected: Taxi
Result: Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented
Contributing factors: Manuals; Airport
Primary problem: Airport

Narrative: After pushback from Gate X at EWR; we called for taxi clearance and Ramp Control cleared us to 'Taxi ROMEO ALPHA; Contact Ground 121.8.' We proceeded to taxi from the ramp onto Taxiway RA. The Ground Control frequency was saturated; so I stopped the aircraft on RA before the Taxiway A / Taxiway B spilt; and waited for an opportunity to request further taxi clearance from Ground Control. When we were able to contact Ground; the Controller was concerned that we may have taxied too far on an 'active taxiway' without talking to Ground. We explained we were stopped and waiting for an opportunity to get a transmission in. The Controller then issued taxi instructions to Runway 4L; and we departed uneventfully.It is unclear where the Ramp Control jurisdiction ends and Ground Control begins. The 10-7C SAFETY ALERT page shows only a small non-movement area which does not include the gates or ramp. This is inconsistent with actual control practices; in which Ramp controls inbound aircraft all the way to the gate. The 10-9 diagram also does not match the 10-7C depiction of Taxiway RA; which is longer than what is depicted on the 10-9. ATC signage for RA also does not match the 10-9. And 'Ramp Control 129.07' is depicted on the 10-7 between Gate 15 and RA; implying that Ramp Control; not Ground; is responsible for those areas even though it is not the same NON-MOVEMENT area depicted on the 10-7C.We followed Ramp Control's instructions to the letter; but Ground Control was not in agreement. Stopping on RA minimized any possible transgression; and when we stopped; we were still in compliance with our last clearance from Ramp Control. Ramp Control did not issue any hold short instructions; but we held short on RA out of an abundance of caution.


Second narrative: Taxiing out of ramp at EWR; we were cleared by Ramp to taxi A RA; contact Ground. We taxied A to RA and radio congestion did not allow contact with Ground. Captain followed sign that had a diagonal arrow RA and stopped abeam Taxiway A in case required to turn on A. Ground called and seemed to think we had entered a taxiway without clearance.I think that was Ground's confusion because we were still on RA/UP and still North of B. Ground said that we were wrong; and should do better next time we come to EWR. After reading 10-9 and 10-7 page including Safety Alert Page still uncertain as to what non-movement area is and what is controlled by Ground. Signage RA on ramp area is also confusing. Did not see any paint on ramp that denotes where Ground controls. Also not clear when look at 10-9; 10-7; and Safety page where NMA starts and Ground Control begins. No signage to advise as well.


Synopsis: Air carrier flight crew; after pushback and start; were unsure where Ramp authority ended and Ground Control authority began. Ground Control advised them they may have taxied too far without talking to Ground. The crew notes that the 10-9 and 10-7C depictions and the airport signage provide conflicting information.