A method for tracking positions of human extremities is disclosed. Classifying a sample vector comprises, with a processor, subtracting a mean value of a number of support vector machine training vectors from the sample vector to obtain a sample difference vector, with a processor, applying a hash function to the sample difference vector to obtain a hashed sample vector, and classifying the hashed sample vector using a classifier model. The notched edge portions are positioned around the periphery of the SIM card and allow a user to pry the SIM card from the wireless communication device.