What's the Difference?

Customer: I need to return a phone I just received.
Me: No problem. What is the issue you're having with the item?
Customer: The memory card don't fit.
me: Oh? Hmm. What model phone do you have?
Customer: The Moto KRZR for AT&T. {It was really unlocked for all GSM carriers, but that is neither here nor there...}
Me: Well, the phone uses a Micro SD card; if you try to use a regular size SD card, it won't fit because-----
Customer [cuts me off]: But AT&T said all memory cards were the same size! The manual says the memory card slot is on the side, but the card won't fit! I can't get service without the card fitting, so I need to return the phone.
Me: ...wait a minute. Do you mean the SIM card, ma'am?
Customer: SIM card, memory card; what's the difference?
Me:.... There are several. The SIM card is the life of the phone, and the memory card is to store information like pictures and ringtones. It's also bigger than the memory card this phone uses. If you try to put the SIM in the memory card slot, it won't fit.
Customer [pauses]: Ohhh, ok. So where does this SIM card go?
Me: The manual will tell you exactly where, but it has a designated slot in the back of the phone, in the battery compartment.
Customer: I knew I should have had my husband do this for me. Thanks! [hangs up]
Me: *head desk*