One more question concerning my Ping?

Before I asked what the problem was with my ping dropping from low ping to high ping.. and now I was wondering maybe it's my router? (I'm not using wireless router I have it plugged in and I'm using Comcast Cable and I'm on the right server.... so there is obviously no other computer on my network..) I think it's my router because I turned off my router for 15 seconds, turned it back on, and got a 20 ping, then a few minutes later it's back up to 500-700... is it a bad connection between my computer and Router? Should I call my ISP?