You have three Samsung A15s on the shelf. Same model, same black, same 128GB. In the stock book they are one line: "A15 128GB black, 3". On Tuesday you sell one. On Friday a customer walks in and says her phone has stopped charging, and it is still under warranty.
Which one did you sell her? Is the phone in her hand the one she bought? If you can't answer that, you are working on trust, hers and your own.
Phones are the one thing in a shop where "three of the same" is never quite true. Each handset is a separate object with its own history. The fix is to give every unit its own identity and write it down at three moments: when it comes in, when it goes out, and when it comes back.
IMEI and serial number are not the same thing
Customers and attendants use the two words as if they mean one thing. They don't.
The IMEI is a 15-digit number that identifies a phone on the mobile network. A dual-SIM phone has two, one for each SIM slot. The first 8 digits name the model, and the rest belong to that one handset. No two handsets should share one.
The serial number is the maker's own number for the unit. It is a mix of letters and digits, its length depends on the brand, and it is often what a service centre asks for. Laptops, tablets, chargers and some watches have a serial number but no IMEI, because they don't connect to the mobile network on their own.
For a phone, the IMEI is the better thing to record. It is the same number on the box, on the phone and in the settings, so you can check it at the counter. Use the serial number for what has no IMEI, and when a maker's warranty is looked up by serial.
Where to read it
There are three places, and all three should agree.
- Dial \*#06# on the phone. The IMEI appears on screen. A dual-SIM phone shows two.
- Settings. Look under About phone on Android, or General and then About on an iPhone. The IMEI and serial number are both listed there.
- The box. There is a sticker with the IMEI, usually with a barcode beside it.
Check the phone against its box before it goes on your shelf. A box holding a phone with a different IMEI is a mismatch you want to find now, while the supplier is still in front of you, not six months later when a customer finds it. It is also the quickest way to spot a box that has been reused for another handset.
Write the number you read from the phone itself, not only from the box. The box can be swapped. The phone can't.
Record every unit on its own line
Three of the same model should not be one line in your stock book. Give each unit a line of its own. This is the format, with invented figures.
| Date in | Model | Colour / storage | IMEI | Cost | Supplier | Status | Sold on | Receipt no. |
|---|---|---|---|---|---|---|---|---|
| 3 Nov | Samsung A15 | Black / 128GB | 35XXXXXXXXXX101 | ₦245,000 | Ikeja supplier | Sold | 5 Nov | 0412 |
| 3 Nov | Samsung A15 | Black / 128GB | 35XXXXXXXXXX218 | ₦245,000 | Ikeja supplier | In stock | ||
| 3 Nov | Samsung A15 | Black / 128GB | 35XXXXXXXXXX344 | ₦245,000 | Ikeja supplier | In stock |
Real IMEIs have 15 digits; the example only shows the shape. What matters is that the sold phone now has a name. Receipt 0412 belongs to the IMEI ending 101, and to nothing else.
Add a column for who served the customer, and one for the customer's phone number if they gave it. Keep the status to a few plain words: in stock, sold, returned, with supplier, in repair. A unit that is in repair is neither on the shelf nor sold, and without a status it just looks missing.
Check it on the way in and on the way out
A record is only as good as the moment it is written. Two habits do most of the work.
On the way in. Read the IMEI from the phone, match it to the box, write the line. Do the whole delivery the same day. If a supplier sends ten phones, you write ten lines. If an IMEI appears twice in your own book, it is a typing slip or a problem with the stock, and either is worth knowing about.
On the way out. Before the phone leaves the counter, the attendant dials \*#06# with the customer watching, reads the number, and writes it on the receipt. The customer sees that the number on the phone, the box and the paper is the same. It takes thirty seconds and it is the best proof you will ever have of what was sold. Our piece on how to write a receipt covers the rest of what goes on one.
Some things have no IMEI: chargers, earbuds, a phone that has lost its box. A numbered sticker of your own does the same job there. Put it on the item, and write the sticker number beside the item in your book. If you are not sure how barcodes work for a shop, how to get a barcode in Nigeria explains it.
A swap or a second-hand phone needs the same line, with one extra step. Ask the seller to dial \*#06# in front of you and compare the result with the box before you pay. If the numbers don't match, don't buy.
The return that goes wrong
Here is why this is worth the trouble. Say you sold a phone for ₦350,000 on Tuesday. The receipt says "Phone, ₦350,000" and nothing else. On Friday the customer brings a phone back, says it has a fault, and wants her money.
Maybe the fault is real. Maybe her own phone was cracked, and on a busy afternoon she has put it in the box and handed you that instead. Maybe it's a cheaper unit from somewhere else. You have no way to show it isn't the phone you sold. If you refuse, you lose a customer and possibly your name. If you refund, you may be out ₦350,000 on a phone worth a fraction of it.
Now the same sale with the IMEI on the receipt. She brings the phone back. You dial \*#06#, and the number ends in 344 while the receipt says 101. The conversation ends quickly, and nobody has been called a thief. Or the numbers match and the fault is real, and you replace the phone or call the supplier with confidence, because you can tell them exactly which unit it was and when it arrived.
It protects the honest customer too. A receipt with the IMEI is her proof that this phone came new from your shop, which is what a warranty claim needs.
When a phone does come back, add to its line what was wrong, what you did, and the date. One IMEI then carries one history: bought on 3 November, sold on 5 November, returned on 8 November with a charging fault, sent to the supplier on 9 November.
The same record answers the question owners dread. You count three A15s on Monday and find two. Without per-unit lines, you know one is gone but not which, and you can't tell a sale nobody wrote down from a loss. With them, you find the line marked "in stock" with no phone on the shelf. You have an IMEI to ask about, and to give the police if it comes to that.
A missing unit with a name is a question you can ask. A missing "one A15" is an accusation with nothing under it. Be fair to your staff here: an unrecorded sale or a phone put in the wrong drawer is as likely as theft.
Count phones by IMEI in your weekly count. Read the number off each phone on the shelf and tick it in the book. It is ten minutes for twenty phones, and the book is right again.
Tabs is our software, and it covers part of this. You can add each phone as its own item. It recognises a 15-digit IMEI when you scan a phone's box or type the number in, a dual-SIM phone's second IMEI has its own place, and an IMEI can't be given to a second item in the same store. A printed or PDF receipt shows each item's barcode under its name. Setting up two of the same model, such as two silver 256GB phones that each need their own barcode, is in sizes, colours and options. The notebook version above works without any of it.
Start with the next phone you receive. Read the number from the handset, match the box, write one line. Put the same number on the receipt when it goes out, and the next time somebody asks "is this the one I bought?", the answer is on paper.
