You should always send relevant information (place, date, altitude, habitate, habit, size of leaves and flowers) for proper documentation, otherwise such photographs are of little use in documentation.
This plant is Vinca major
But next time send photograph with details.
Dr. Gurcharan Singh
Retired Associate Professor
SGTB Khalsa College, University of Delhi, Delhi-110007
Res: 932 Anand Kunj, Vikas Puri, New Delhi-110018.
Phone: 011-25518297 Mob: 9810359089http://people.du.ac.in/~singhg45/