The short answer is, yes, you'll be able to use your existing installed cable when replacing your QSEE DVR in most cases. It's worth noting, however, that QSEE typically sold systems with thin pre-made cable that couldn't support ultra HD 4K quality. If you want to update any of your cameras to 4K or 8MP, you'll need a high-quality roll of solid copper RG59U cable and connectors.