Hi Bewilderdone. I understand.. There is always more to the story. As a parent I find myself, between a rock and a hard place, I never what to tell it all for two reasons, I don't want anyone to judge my son, and I don't want to admit I failed...
take the phone away and put it somewhere she can not access it. Tell her it is gone and when she has pulled her weight and you feel she has made amends for what ever she has truly done then you decide it you want to give it back. I wish i had the guts to do that with my son. But I didn't and now I realize what a mistake it was. And that my friend is a long story. If you ever want to chat just send me a message. I am agood listener even though my problems are big, I deal with others better than my own.
Take care

Anytime I doubt my son (and now that he's 15 I find it to be often although he's never given me reason to) I double check things. The other day for example he wanted to go spend time with his girlfriend. I said no. Then he asked if he could go to his other friend's for the night. I said sure but his mom needs to call me first. I get this story "His mom isn't home she might not be able to call" I said "If he can get his mom to tell him yes you can stay the night, then he can get her to call me"... Well about 30 minutes later his mom called. He wasn't pulling a fast one on me. I really thought he might be too. But he wasn't. He knows that I"ll double check things out on a whim and I think that helps to keep him honest with me. Next time your daughter says it's somewhere tell her you're gonna go look and if she's lying you will smash it with a hammer, and she'll have to wait till she's old enough to have a job and pay for her own phone to get another one.. Then ask her once again where it is.. If she still says it's there go check. If she changes her story say I'm glad you told me the truth. Please go get it and bring it to me. It's going to stay with me for awhile. But next time you lie to me the first time, I'm going to smash it. At least that's what I would do..

Oh and don't live your life or make your discipline decisions based on fear of what she might do. She's going to do what she's going to do no matter if you smash the phone or not. But if she feels that she can control things by having you scared, then that makes her life easier. Don't let your children run the household. You have to do what's right. If she rebels then you take another step based on that.

I have to agree with the others about physically taking the phone and putting it some where she will not find it. Even if that means you carry it for a couple days. I have done exactly that with my daughter. I grounded her from the phone and one evening she got a text and picked it up and read the message in front of me. I took it right then. She said she didn't know that she couldn't read the messages. LOL! So now I will take the phone myself. And if a message comes through I will read it and it drives her nuts to watch me read her messages and she can't. I only had to do that once. But I will do it again if need be. Good Luck!

Trust but verify. I would not be too surprised a teen lies to you.