$340 seems a bit high for a phone that you've used for over a year. Especially considering there are refurbished, used and even a couple of barely touched iPhone 7's for even less than you are asking. You registered your account just a couple of days ago, with this thread being the only couple of posts that have been produced by your account.
Are you accepting escrow?
At least you added your username and the date to the picture, but when the first person asked about escrow you asked for a PM. You should make this information public, since there are limitations on your PMs and there will be more people wondering about this.
The price is negotiable or fixed?Also the phone is unlocked or have a straight plan?
Everything is negotiable. The OP says the phone is Unlocked.