The serial concatenation of simple binary convolutional codes through an interleaver is a technique that yields, through iterative decoding, performance similar to, and in some cases better than, those of turbo codes (parallel concatenated convolutional codes). The design of serially concatenated codes with short and medium interleavers is considered in this paper; comparisons between union bounds, maximum-likelihood sequence decoding and iterative decoding are presented. An example of code and interleaver optimization is reported. An alternative scheme to current GSM standard channel coding is also analysed.