If you connect Mediant 1000 M1k to a PoE enabled port on a switch, you might lose network connectivity to Audiocodes every 20 seconds. To resolve this issue, simply disable PoE feature on the switch and that should fix the problem.
I had the same issue with Audiocodes when I had it connected to Juniper EX 3300 PoE switch and as soon as PoE was disabled it started to work.