A lot of good information here. Here's my situation which sounds a bit unique. All flights are on single PNR issued by United for an award ticket in J class. I can see all 4 flights on airindia.com when using the AI PNR provided by United.

KTM-DEL AI 216 15:35-16:50
DEL-BOM AI 24 18:00-20:10
BOM-YYZ AC 47 23:30-05:15+1
YYZ-PHX AC 1837 09:15-10:57

So I'm going from international to "domestic" to international (most other posts on this thread have been about I-to-D or vv; I haven't noticed an I-to-D-to-I scenario). I assume based on previous information in this thread that AI 24 is one of the AI flights that's treated as international and therefore I won't need to go through immigration/customs at DEL (which I guess also means I don't need a transit visa). So unless there's a major delay on the KTM-DEL flight (which is always a possibility cause ... KTM), 70 minutes of connecting time would sound like it should be enough. But it also sounds like part of that might depend on whether I already have my DEL-BOM boarding pass or whether I have to stand in line at the international transfer desk at DEL T3.

Does anyone know which boarding passes AI will give me at KTM? Will it be all 4 passes, just the 2 AI passes, or only KTM-DEL? Will my baggage tags show PHX as the final destination (I know I'll have to clear customs in YYZ)? If AI only issues the AI boarding passes, will there be an AC agent at the BOM transfer desk to issue my AC passes or will I get those at the gate? Thanks in advance for any assistance offered.