An Air Carrier First Officer GPS jamming in VIDF international airspace.

Narrative

I was on this leg and had the first break. Upon returning to the flight deck after the 1st break I was briefed that the aircraft had GPS L; ADS-B OUT L; and TERR POS EICAS messages displayed since shortly after departure. This status continued throughout the entire flight. ADS-B and GPS failures are somewhat expected in the area of the country of Turkey as GPS jamming is typical in that part of the world so it seemed unusual that these messages appeared so early in the flight and lasted as long as they did. The RC and I communicated to Dispatch several times throughout the flight informing them of the status of our aircraft. We were repeatedly assured that these aircraft system outages are known by the company; common on these routes and 'should return to normal status' soon. On a previous flight from DEL to ZZZ I was told that the company is working on new procedures for these types of events and that guidance and new procedures will be printed and released 'soon'. We contacted Dispatch and Maintenance on SATCOM and we were informed that there is currently no procedure or checklist in the books for pilots to correct these issues while in flight. We expressed concerns about our Oceanic Crossing and RVSM airspace without these systems working properly. We asked for fuel planning numbers to be run at 28000 ft. in order to make the crossing outside of RVSM airspace and those numbers didn't work for our weight to reach our destination ZZZ or a closer airport such as ZZZ1. A diversion to ZZZZ was recommended by Dispatch if we felt that we could not legally continue the flight. While it is true that we do not need GPS to make an oceanic crossing as the Dispatcher made clear to us and wrote 'check your manuals'; we did not have enough fuel to do so. We were sent a message that we should request our clearance with BIRD [FIR] making them aware of our reduced equipment status and if their workload and level of aircraft traffic allowed; we may be able to complete the Oceanic Crossing at our planned and dispatched altitude and Mach number. We were sent a message from Dispatch; we would be able to complete our flight as planned with permission from BIRD if workloads allowed. That permission was granted and we made our Oceanic Crossing as planned. I was back on my 2nd break by the time the oceanic clearance was requested and received. When I returned from my 2nd break we were in the middle of our crossing. The EICAS messages remained. GPS message did finally go away I believe once we were well over Canadian land for over an hour or so. The aircraft was able to use ground based VOR positioning to keep RNP and ANP within acceptable limits. I fly New Delhi trips at least once a month for a while now. I've seen these messages before but never this early in the flight and remain for so long during the flight. Perhaps there is something or someone or some entity that is GPS jamming aircraft in India; soon after departure. Who knows. I realize that it is expected near Turkey. I've also done a bit of flying to Tel Aviv and it's expected; but this was unusual. On a previous flight when this similar situation occurred we were strongly urged to reset the GPS circuit breakers in flight to avoid diverting to ZZZZ1. Really hard to say how to prevent it. Having an approved; written and legal procedure or checklist to handle this type of situation would be helpful though. Much better and reassuring than just getting messages from Dispatch that this is a known issue/occurrence and systems should come back 'soon' before the oceanic crossing.