AI agents for business finance: what they can and can't do
What AI agents can do in bookkeeping, close, collections and compliance today, where a person must stay in charge, and how to judge a product.
The short answer
Use USSD with your own SIM in the borrowed phone if you can, because it leaves no saved password or session behind. If you must use internet banking, open the bank’s site in a private window, refuse to save the password and log out properly. Avoid installing your bank app there, as banks that allow one device at a time may sign out your own phone.
Why a borrowed phone is riskier than it looks
Your own phone is set up around you: your screen lock, your fingerprint, your SIM, your app passcodes. A friend’s or relative’s phone is set up around them. When you log in to your bank there, three things can go wrong even if the owner is completely trustworthy.
- Something stays behind. A browser can keep you logged in, remember your password, or hold the pages you visited. An app can keep your session alive in the background.
- The phone itself is not clean. You have no way of knowing whether it has a screen-recording app, a keyboard app that logs what you type, or remote-access software someone talked the owner into installing.
- Your own phone can lose access. Banks increasingly tie the app to one device. Reports of the CBN’s BVN rules from 1 May 2026 (Channels TV, April 2026) say banking apps should work on one device at a time, that logging in on a new device deactivates the old one and triggers checks, and that a ₦20,000 limit applies in the first 24 hours on a new device. Logging in on a friend’s phone could therefore lock you out of your own for a day.
So the first question is not "how do I do this safely" but "do I need to log in at all".
Option 1: use USSD with your own SIM
If you just need to send money, buy airtime or check a balance, USSD is usually the safer choice on someone else’s phone, for a simple reason: it leaves nothing behind. There is no password to save, no app session and no browser history. Each session ends when the menu closes.
Most bank USSD services only work from the phone number registered on your account. That means taking your SIM out of your own phone (if it was damaged or out of battery) and putting it into the borrowed handset, or using a dual-SIM slot. The USSD PIN is still needed for every transfer, and it is typed into a menu that disappears.
- Cover the screen and keypad when typing your USSD PIN.
- After you finish, delete the outgoing USSD entries and any bank SMS replies from the phone’s call log and messages, because the confirmation text may show your balance.
- Take your SIM back out before handing the phone back.
USSD has its own fraud risks, covered in USSD banking fraud, but on a borrowed phone it exposes far less than a full login.
Option 2: internet banking in a private browser window
If you must see full statements or do something USSD cannot, use the bank’s website in a private (incognito) window rather than installing the bank’s app.
- Open the browser and choose "New incognito tab" (Chrome) or "Private" (Safari). Private windows are designed not to keep your history, cookies or form entries after you close them.
- Type the bank’s web address yourself. Do not follow a link from a message or a search advert.
- When the browser offers to save your password, choose "Never" or close the prompt.
- Use the bank’s token or in-app approval where asked. Never read an OTP out to anyone in the room.
- When done, use the site’s "Log out" button, not just the back button, then close every private tab.
Option 3: the bank app (only if you have to)
Installing your bank app on another person’s phone is the riskiest of the three. If there is no other way:
- Install it only from the official app store and check the developer name; see how to check the real banking app.
- Do not enable fingerprint or face login on that phone. The owner’s biometrics would then work on your bank app.
- Expect your own phone to be signed out if the bank allows one device at a time.
- When finished, log out inside the app, then uninstall it. Uninstalling alone may not end the session on the bank’s side, so also remove the device in your bank’s "manage devices" setting when you are back on your own phone, if your bank offers one.
Before you hand the phone back
- Log out of every bank site or app.
- Close all private tabs; uninstall any bank app you installed.
- Check the browser’s saved passwords list and delete yours if it slipped in.
- Delete bank SMS messages, USSD history and any screenshots you took of receipts.
- If you used your SIM, take it out.
- Back on your own phone, change your password if you typed it on a device you were unsure about.
If something went wrong
If you think your details were seen or saved, or you later see a transaction you did not make, block the account first and ask questions later. Several banks publish emergency USSD codes for this; for example, Access Bank’s FAQ says *901*911# blocks the account and works from any phone with your USSD PIN, and Stanbic IBTC lists *909*1*911#. Then follow what to do in the first hour.
Where Pryme fits
Pryme sign-in approval uses an authenticator app rather than SMS codes, and transfers need your transaction PIN, so a session left on a borrowed phone still cannot move money without them. The security page explains the set-up.
Questions people ask
Is it safe to log in to my bank app on my friend’s phone?
It carries real risk: sessions and passwords can be left behind, and the phone may not be clean. Banks that allow one device at a time may also sign you out on your own phone. Use USSD with your own SIM where possible.
Does incognito mode protect my bank login?
It stops the browser keeping your history, cookies and form entries after you close the window. It does not protect against malware already on the phone.
Can I use my USSD code on another person’s phone?
Usually only with your own SIM in it, because most bank USSD services work only from the registered number. Your USSD PIN is still required for transfers.
I logged in on a friend’s phone and forgot to log out, what do I do?
Change your password and PIN from your own device, remove the unknown device in your bank app’s device settings if offered, or call your bank to end the session.
Sources
- Channels TV: What you must know as CBN tightens BVN rules from May 1, 8 Apr 2026 · accessed Oct 2026
- Access Bank: USSD banking FAQ · accessed Oct 2026
- Stanbic IBTC: USSD banking · accessed Oct 2026
This article is general information, not financial, legal or tax advice. Products described are provided under the terms on this site and are subject to regulation and eligibility.