We implemented three real-time DTMF detection schemes, and analyzed their performance. We chose an observation time (block size) to optimize the performance subject to real-time constraints. The MUSIC DTMF decoder complies with CCITT Q.24 standards, but is the most expensive to implement on an embedded DSP processor. Although easier to implement, neither the Goertzel nor the NDFET DTMF decoders can satisfy the standards, due to poor frequency resolution and high SNR requirements (50 dB), respectively. The hand-coded implementations are faster and require less memory, but the Ptolemy designs can be reused and retargeted to a variety of implementations.