The attack happened Dec. 3rd at about 5 a.m.
Police say the female victim was approached by two women and a man who dragged her onto the platform at the 125th Street and St Nicholas Avenue subway station, punched her and forcibly removed her cell phone.
The woman suffered minor injuries.
Anyone with information is asked to call Crime Stoppers at (800) 577-TIPS (8477).
The public can also submit their tips by logging onto Crime Stoppers' website at http://www.nypdcrimestoppers.com or by texting their tips to CRIMES (274637), then enter TIP577.
All calls are strictly confidential.