I did something similar to friend of ours similar to what the OP plans to do to. We always played pranks on each other and not just on Aprils Fools Day.
This was many years back mind you. We have a friend who is a huge Dead Head. So tickets for a concert where getting ready to go on sale so he took the morning off from work so he could call right as they went for sale (this was before the internet is what it is now). He would call and it would be busy. Call back, busy. So on and so forth. He finally got through and got the 4 tickets (we were going with them). He was over the moon so off to work he goes. But before he left he called us to let us know he got the tickets.
So while he was at work I called his house phone, disguised my voice and left a message that I was calling from Ticketmaster and there was a problem with his order. Sid there was a computer glitch and even though we said there were tickets available there really wasn't. We re very sorry, we will refund you card. I went on to say if he has any questions please call us at 1-800-555-5555 (which was actually our phone number, minus the 800 part of course. I figured he would have caught that and realized it was a joke. Well, he didn't.
He called the number and of course it didn't work so he then called the Ticketmaster number. Oh my gosh! He went up one side of them and down the other. He was furious. They finally were able to get a word in and assured him there was not a problem with the tickets and everything was fine. They didn't know why he could have received such a message. After a while he finally calmed down and called us to tell us what happened. That's when I let him in on the joke.
I felt so bad. What I thought would be funny ended up not being. He was so upset. Even now, a good 20 years later it still gnaws at me what I did. After that I stuck to things like moving things around in his cabinets and short sheeting the bed. The last one was always a fun one after a night of drinking.