You should provide some time/username-stamped pics. Not many people will bid on a phone that might not exist and with an undisclosed reserve. Also, if you have a reserve price why don't you just sell it for that amount instead?
I'm selling my phone only with a trusted escrow on here so that shouldn't be a problem. In this case, the buyer and seller are both protected so that shouldn't be a concern.
I want to see how much my phone will sell for and if it meets the reserve price then I will sell it at that. I do not have to disclose my reserve price at all.