There is pre-paid taxi stand outside the station from where pre-paid taxis are easily available. I have availed myself of this facility only today after getting off from 13168 Agra Cantt Kolkata Express.
There are buses of different routes available from near the station. The bus routes are :
(1) K1 ( Kolkata Station -Ultadanga- New Town -unitech) at an interval of about ten minutes
2)...
more... 007 (Makrampur - Kolkata Station via Tematha, Sonarpur Station, Kamalgazi, Garia, Patuli, Hiland Park, Mukundapur, Kalikapur, Ruby Hospital, Science City, Chingrighata, E.M. Byepass, Ultadanga, Khanna, Shyambazar)
3) Sonarpur Station to Kolkata Station via Kamalgazi, Garia, Patuli, Hiland Park, Mukundapur, Kalikapur, Ruby Hospital, Science City, Chingrighata, E.M. Byepass, Phoolbagan, Kankurgachi, Ultadanga, Khanna, Shyambazar
4) New Garia Station to Kolkata Station via EM Bypass
5) JM2 (Malancha - Kolkata Station via Harinavi, Rajpur, Kamalgazi, Dhalai Bridge, Patuli, Hiland Park, Mukundapur, Kalikapur, Ruby Hospital, Science City, Chingrighata, E.M. Byepass, Ultadanga, Khanna, Shyambazar)
If you reach near RG Kar Medical College and Hopital, you get myriads of buses plying on different routes. Sometimes autos are also available near Kokata Station.