What Is PDP Authentication Failure? Causes and Fixes on iPhone and Android

PDP authentication failure means your carrier's network refused your phone's request to start a mobile data connection. Your phone asked to go online, the network checked the details, and the check failed. The cause is usually wrong APN settings, a line or data plan that isn't active, data roaming that's off abroad, or a problem on your carrier's side. Signal bars can look fine while mobile data doesn't work at all. Here's what PDP means, why the authentication fails, and how to fix it on iPhone and Android.

What is PDP authentication failure?

PDP stands for Packet Data Protocol. Every time you turn on mobile data, your phone asks the network to open a data session, called a PDP context. With that request, your phone sends its data settings: the APN (Access Point Name) and, for some carriers, a username, a password and an authentication type.

The network checks those details against your line. If something doesn't match, it rejects the request. In the mobile network standards, this rejection has its own reason code: "user authentication failed" (3GPP TS 24.008, 3GPP TS 24.301). Your phone may then show it as "PDP authentication failure", and you get no mobile data.

What does PDP mean on a phone?

On a phone, PDP is about your mobile data connection, not your calls or texts. When your phone has an active PDP context, it can use mobile data. When the PDP request fails, apps, browsing and messaging apps stop working on mobile data. Wi-Fi isn't affected.

What is a PDP network or PDP context?

A PDP context is the data link between your phone and your carrier's network, set up through the APN. The name comes from 2G and 3G networks. On 4G and 5G, the same idea is called a PDN connection or a PDU session, but many phones and carriers still say "PDP". The APN protocol setting on Android still uses PDP types from these standards, such as IPv4, IPv6 or IPv4/IPv6 (Android Developers: APN fields).

Where you see the error

On iPhone, it often appears together with the message "Could not activate cellular data network" (or "mobile data network"). That message has its own guide: how to fix "Could not activate cellular data network". On other phones, you may simply see signal but no mobile data.

Why does PDP authentication fail?

These are the usual causes, from the most common to the least:

• Wrong APN settings: the APN, username, password or authentication type doesn't match what your carrier expects. This often happens after you typed an APN by hand, copied one from a random website, or moved your SIM to a new phone.
• Your line isn't fully active yet: a new SIM or eSIM, or a number transfer, that your carrier hasn't finished setting up. You may also see "SIM not provisioned".
• No data on your plan: your data allowance is used up, your top-up or bundle has expired, the bill is unpaid, or mobile data isn't part of your plan.
• You're abroad and roaming isn't working: data roaming is off on your phone, or roaming isn't included on your plan.
• Old settings on your phone: outdated carrier settings or software. On iPhone, an iOS update also resets APN details you entered by hand (Apple: View and edit your APN).
• A problem on your carrier's side: an outage, an account restriction, or a phone that's blocked from the network.

Quick fixes to try first

These work on any phone. After each step, turn Wi-Fi off and open a web page to test your mobile data.

1. Turn Airplane Mode on, wait at least 15 seconds, then turn it off. Your phone then sends a new data request (Apple: If you see SOS, No Service, or Searching).
2. Restart your phone.
3. Check that mobile data is on, and on a phone with two SIMs or eSIMs, that the right line is used for data.
4. Check that you have data left in your carrier's app or account.
5. Abroad? Turn on data roaming for the line you use for data.
6. Update your phone and, on iPhone, your carrier settings.

Still no data? Go to the steps for your phone below. If your data stopped working without any error message, our guide on why your mobile data isn't working covers more general fixes.

How to fix PDP authentication failure on iPhone

Depending on your region and iOS version, the menu is called Cellular, Mobile Data or Mobile Service. The steps are the same on iPad with cellular.

1. Check Cellular Data and the right line

Go to Settings > Cellular and make sure Cellular Data is on. If you use two lines, tap Cellular Data and pick the line that should handle your data (Apple: Use cellular data on your iPhone or iPad).

2. Turn on Data Roaming if you're abroad

Go to Settings > Cellular, tap your line, then Cellular Data Options and turn on Data Roaming. Check first that roaming is included on your plan, or you may pay extra.

3. Update your carrier settings and iOS

Connect to Wi-Fi and go to Settings > General > About. If a carrier settings update is available, you'll see a message to install it (Apple: Manually update carrier settings). Then check Settings > General > Software Update.

4. Check or reset your APN

Go to Settings > Cellular > Cellular Data Network (on some iPhones: Mobile Data Options > Mobile Data Network). You only see this screen if your carrier allows it (Apple: View and edit your APN).

• If you changed something before: tap Reset Settings to go back to your carrier's default APN.
• If your carrier gave you an APN: enter the APN, username and password exactly as written, including upper and lower case. Leave the username and password empty if your carrier doesn't give you any.

Not sure what each field means? Our guide on what an APN is and how to change it walks you through it.

5. Reset network settings

Go to Settings > General > Transfer or Reset iPhone > Reset > Reset Network Settings (Apple: Return iPhone settings to their defaults). This also removes your saved Wi-Fi passwords. Don't tap Erase All Content and Settings or delete your eSIM.

How to fix PDP authentication failure on Android

Menu names change a little between brands and Android versions. If you can't find a menu, open Settings and search for it.

1. Check mobile data, the line and roaming

• Samsung Galaxy: go to Settings > Connections > Mobile networks and turn on Data roaming if you're abroad (Samsung: Turn data roaming on or off).
• Google Pixel: go to Settings > Network & internet > SIMs, pick your line, and check that Use SIM and Mobile data are on (Google: Fix mobile connectivity issues). Turn on Roaming on the same screen if you're abroad.

2. Check the APN and authentication type

This is where most PDP authentication failures get fixed on Android.

1. Open the APN list. On Samsung: Settings > Connections > Mobile networks > Access Point Names. On Pixel: Settings > Network & internet > SIMs, pick your line, then Access point names.
2. Check that the APN your carrier uses is selected.
3. Tap it and compare the APN, Username, Password and Authentication type with the values from your carrier's official website.
4. Save, select the APN, and restart your phone.

The authentication type tells your phone how to send the username and password to the network. Android offers None, PAP, CHAP and PAP or CHAP. PAP and CHAP are two different login methods, and a mismatch alone can trigger the error. Use the type your carrier gives you. If it gives none, leave the field as it is.

Did you change the APN yourself? Tap the three-dot menu in the APN list and choose Reset to default (Samsung: Troubleshoot no network signal). This brings back your carrier's settings.

3. Reset mobile network settings

• Samsung Galaxy: Settings > General management > Reset > Reset mobile network settings (Samsung).
• Google Pixel: Settings > System > Reset options > Reset Mobile Network Settings (Google: Connect to mobile networks on a Pixel phone).

When to contact your carrier

If none of this works, the problem is probably on your carrier's side. Only your carrier can see your account and the reason it rejected your data request. Ask them to check that (Apple):

• your account is active and paid up,
• your SIM or eSIM is fully activated (provisioned) on their network,
• your plan includes mobile data, and roaming if you're abroad,
• your phone isn't blocked or barred from their network,
• the APN, username, password and authentication type you should use.

Tell them you see "PDP authentication failure". It points them straight to the data login on their side.

PDP authentication failure abroad or on a travel eSIM

Getting the error just after landing? With your home SIM, check that roaming is on your plan and that Data Roaming is on. With a travel eSIM, go through these first:

1. The travel eSIM line is turned on.
2. Data roaming is on for the travel eSIM. A travel eSIM usually needs it, even in the countries your plan covers. See the correct roaming settings for an eSIM.
3. The travel eSIM is selected for mobile data, not your home line.
4. Your plan is active and has data left.
5. Only enter an APN your eSIM provider gives you. Most travel eSIMs set it up for you when you install them.

Still stuck? Our guide to an eSIM that's not working has more fixes, and if your eSIM never activated at all, see how to fix an eSIM that's not activating. Using a SimOptions eSIM? Contact our support team before you change any APN.

Planning a trip? A data eSIM for your destination keeps your home SIM in your phone for calls and texts, and you can install it on Wi-Fi before you leave.

Data-only eSIMs for Europe, Asia and the USA · Going somewhere else? Find your destination

FAQs

What does PDP authentication failure mean?

It means your carrier's network rejected your phone's request to start a mobile data session. The data details your phone sent, like the APN, username, password or authentication type, didn't pass the network's check, or your line isn't allowed to use data right now.

What does PDP stand for?

PDP stands for Packet Data Protocol. A PDP context is the data session your phone opens with the network every time you use mobile data.

Why does my iPhone say PDP authentication failure?

Usually because of wrong APN details in Cellular Data Network, an outdated carrier settings file, data roaming that's off abroad, or a line that isn't fully active. Reset the APN settings, update your carrier settings and iOS, and contact your carrier if the error comes back.

How do I fix PDP authentication failure on Android?

Open Access Point Names, check that the APN, username, password and authentication type match your carrier's official values, or tap Reset to default. Then restart your phone. If that doesn't help, reset your mobile network settings.

Should I choose PAP or CHAP?

Use the authentication type your carrier gives you. If your carrier doesn't give one, don't change the field. A wrong choice can cause the error you're trying to fix.

Does PDP authentication failure affect calls and texts?

The error is about your mobile data connection. If calls and texts still work, the problem is most likely your data settings or your data plan, not the SIM itself.

What does "SIM not provisioned" mean?

It means your carrier hasn't activated your SIM or eSIM on its network yet. Wait a little after setting up a new line, restart your phone, and contact your carrier if it doesn't change.

Can a travel eSIM show PDP authentication failure?

Yes, like any SIM. The usual causes are data roaming switched off for the eSIM, the wrong line selected for mobile data, or an APN that was changed by hand. Check those first, then contact your eSIM provider.