Estimating the quality of VoIP-transmitted speech is the subject of this paper. We present a loss-based technique that allows a single–sided quality approximation of the ITU-T P.862 (PESQ) standard. Our focus is to provide a simple, humaninterpretable voice quality metric in real-time at a receiver. Therefore, our quality metric has to offer low computational complexity and need to work without the reference signal needed when using PESQ. The contribution of this work is a real-time PESQ-like quality measure that can be simply implemented in a mobile handset. We verify our solution across a wide range of network conditions and show it to give acceptable estimations of the perceived quality.