Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface; Training / Qualification; Workload
Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Environment - Non Weather Related; Human Factors
The flight plan had us going straight across via ZZZZZ so minimum time to coast out. I logged us into CPDLC with ZZZZ Oceanic ATC Operations and we did the circle and tick procedures. Then shortly before ZZZZZ ATC re-routed us over ZZZZZ1 and then told us service terminated; squawk XXXX. We dialed up XYX.Z and XYA.Z on the radios. This was my first flight in over 3 months due to COVID schedule reductions. In the process of all of this; we forgot to get a SELCAL Ck with ZZ Radio. I caught this later in the flight and we did the SELCAL check with ZZ Radio. Flight continued uneventfully.We got busy with multiple tasks in a short period of time and overlooked the SELCAL check. I was using the ZZZ Reference Ck list on my iPAD but since you can't check off the items on the iPad it's not as effective as using the actual paper copy. Also; having not flown in so long creates another challenge as I had probably lost some of my regular flow that comes with flying more regularly. These are pilot not flying tasks but as the Captain; it is my responsibility to make sure they get done.Lessons learned: Be sure to use the paper copy of the Reference Guide checklist. There is great value in being able to look and see if any check marks are missing on the checklist.
Air carrier Captain forgot to do a SELCAL check and cited as contributing factors multiple tasks in a short period and having not flown in a long time.