If you cannot see the time-table properly, then i am sorry but you are wrong. Delhi's Terminal 3 is now the Main Hub of Air India and is going to be connected to Hyderabad, Chennai, Kochi, Ahmedabad apart from Amritsar, Kolkata and Mumbai

AI633 = Ahmedabad-Delhi
AI639/187 = Amritsar-Delhi (AI187 Amritsar-Delhi Leg is on A320, Delhi-Toronto on Boeing 777-300ER)
AI623 = Banaglore-Delhi
AI643 = Chennai-Delhi
AI127 = Hyderabad-Delhi (AI127 Hyderabad-Delhi leg is on A320, Delhi-Chicago on Boeing 777-300ER)
AI693 = Kochi-Delhi
AI681 = Kolkata-Delhi
AI101/143/314/348 = Mumbai-Delhi (Except AI101, all the remaining Mumbai-Delhi flights are on a A320 family aircraft, it is from Delhi, passengers board Boeing 777s/Airbus A330s to go to Paris, Hong Kong, Osaka, Shanghai)

When we say these Cities are connected to Delhi, They are operated on Airbus A320 family aircraft using Air India Callsign and Code

You don't always have references for each and every route, you have to check the time-table and schedule(  )