Clear low frequency (typically 5-25 kHz) coherent type-I ELM precursors have been identified in JET. They are detected through various diagnostics, especially in the ECE and Mirnov signals, but also on the SXR cameras and the multichannel O-mode edge reflectometer. The modes propagate in the direction of the ion-diamagnetic drift and are usually accompanied by a slight rise in the Da-signal. A whole spectrum of toroidal mode numbers in the range 1-14 has been found, and first parametric studies revealed that seems to be mainly determined by the pedestal collisionality, with increasing n leading to higher n-numbers. The modes have a kink-like structure and are localized to a few cms inside the separatrix, in the pedestal region. The duration of the precursor before the ELM crash varies greatly: Usually, the precursors appear ~0.2-1ms before the ELM, but there are many cases where they become destabilized several tens of ms in advance of it. These longlived precursors can grow and shrink repeatedly before the ELM and change their frequency and dominant n-numbers rapidly. The low-n precursors are known to be external kinks, while comparison with stability calculations suggest the higher-n precursors modes could be mixed ballooning-kink modes. A great number of discharges has been analysed, and the precursors could be detected prior to most type-I ELMs, while prior to type-III ELMs the modes were not encountered.