Emerging systems such as Internet-of-things (IoT) and machine-to-machine (M2M) communications have strict requirements on the power consumption of used equipments and associated complexity in the transceiver design. To meet these requirements, we propose a novel index modulation (IM) scheme, namely pulse index modulation (PIM) for single-input single-output (SISO) schemes. The proposed model uses well-localized and orthogonal Hermite-Gaussian pulses for data transmission and provides high spectral efficiency owing to the Hermite-Gaussian pulse indices. Considering the high complexity of maximum-likelihood (ML) detector, we propose a matched filtering-based low complexity detector to implement the PIM scheme in practice. Besides, it has been shown via analytical derivations and computer simulations that the proposed PIM system has better error performance and considerable signal-to-noise ratio (SNR) gain compared to existing spatial modulation (SM), code index modulation aided spread-spectrum (CIM-SS), CIM-SM, and traditional-ary systems.