H2O Wireless APN Settings (2026): Fix Data, MMS, and Hotspot

"H2O Wireless SIM activated, data works on Wi-Fi but cellular won't load anything. What APN am I supposed to use?"

H2O Wireless runs on AT&T's network and uses a specific MVNO APN that does not match either AT&T postpaid or AT&T's prepaid brands. The value (att.mvno) is short and easy to mistype, and the MMS server still routes through AT&T's legacy Cingular-era infrastructure.

Here is the verified setup for Android and iPhone, plus what to check when MMS fails on H2O specifically.

H2O Wireless Quick Facts

• H2O Wireless is a US prepaid MVNO that runs on AT&T's network. Coverage and bands match AT&T's footprint in most markets.
• The Android APN is att.mvno in lowercase. Capitalization breaks the entry. The MMS server is at mmsc.cingular.com, a legacy AT&T address that still routes H2O MMS correctly.
• iPhones running iOS 15 or later usually auto-configure H2O settings through Apple's carrier-bundles system. Manual editing is rarely needed.
• 5G coverage on H2O matches AT&T's 5G footprint. The same APN handles 4G LTE and 5G traffic.

Reaching the APN Editor

If data fails entirely, the APN value or MCC/MNC pair is the likely culprit. If only MMS fails, focus on the MMSC, MMS Proxy, and MMS Port fields below. Both are case-sensitive on AT&T's network.

Android

1. 1.Open Settings
2. 2.Tap Network & Internet (or Connections on Samsung)
3. 3.Tap Mobile Networks, then your H2O SIM if dual-SIM
4. 4.Tap Access Point Names
5. 5.Tap the three-dot menu, then New APN
6. 6.Enter the values from the Android list below
7. 7.Tap Save, then select the new APN to activate it
8. 8.Restart the phone or toggle Airplane Mode for 20 seconds

iPhone and iPad

1. 1.Open Settings
2. 2.Tap Cellular or Mobile Data
3. 3.Tap Cellular Data Options, then Cellular Network
4. 4.Enter the iPhone values from the list below
5. 5.If the Cellular Network option is missing, run Reset Network Settings and check for a Carrier Settings update

H2O Android APN Values

Use these for Android phones, tablets, and hotspots connected through an H2O Wireless SIM:

• Name: H2O Wireless
• APN: att.mvno
• Proxy: <Not set>
• Port: <Not set>
• Username: <Not set>
• Password: <Not set>
• Server: <Not set>
• MMSC: http://mmsc.cingular.com
• MMS proxy: wireless.cingular.com
• MMS port: 80
• MCC: 310
• MNC: 410
• Authentication Type: None
• APN Type: default,supl,mms
• APN Protocol: IPv4/IPv6
• APN Roaming Protocol: IPv4/IPv6
• Bearer: Unspecified

H2O iPhone APN Values

iPhones running iOS 15 or later usually auto-configure these. If manual entry is required:

• Cellular Data / Mobile Data (APN): att.mvno
• Username: <Not set>
• Password: <Not set>
• MMS:
  • APN: att.mvno
  • MMSC: http://mmsc.cingular.com
  • MMS Proxy: wireless.cingular.com
  • MMS Max Message Size: 1048576
  • MMS UA Prof URL: http://www.apple.com/mms/uaprof.rdf
• Personal Hotspot: APN = att.mvno, Username and Password = <Not set>

International Calling on H2O

H2O Wireless plans bundle international calling allowances to many countries, especially in Latin America, the Caribbean, and parts of Asia. None of that requires special APN configuration. The minutes count against your plan pool when you dial an international number through the standard phone app.

For international roaming (using H2O while outside the US), check the H2O account dashboard for active destinations. Coverage and pricing depend on AT&T's roaming agreements with local carriers in each country. The APN Roaming Protocol may need to be set to IPv4 only for some destinations.

If your plan includes international calling and a specific country is not working, the issue is usually plan-level (not all destinations are covered on all plans) rather than APN-level. Verify your plan coverage before troubleshooting the settings.

H2O Connection Fixes

• After saving the Android APN, reboot the phone. H2O sometimes does not switch to the new entry until the device re-registers with AT&T's network.
• Confirm the APN value is att.mvno in lowercase. Capitalization breaks the entry on AT&T's network.
• If MMS fails, double-check the MMSC and MMS proxy. H2O uses the legacy Cingular-era hostnames (mmsc.cingular.com and wireless.cingular.com), not the newer AT&T-postpaid values.
• For iPhones, install any pending Carrier Settings update at Settings > General > About. The prompt appears for about 15 seconds.
• If your phone is locked to AT&T postpaid or another AT&T-network carrier, request an unlock first. Locked phones sometimes refuse H2O's profile.
• Make sure the phone supports AT&T's network bands, especially the 5G mid-band that drives faster speeds.
• If activation just completed and data is still failing, give it 24 hours. H2O's back-end can take time to fully provision a new line.

Frequently Asked Questions

Why does H2O use Cingular-era MMS servers?

AT&T inherited Cingular's MMS infrastructure when the two companies merged in 2007, and the hostnames stayed the same for backward compatibility. H2O Wireless inherits this legacy because it routes MMS through AT&T's wholesale platform.

Is H2O Wireless on AT&T or AT&T Prepaid?

H2O is an MVNO on AT&T's network, separate from AT&T Prepaid. The underlying infrastructure is the same, but the billing and account systems differ. H2O has its own plans, customer service, and APN values.

Do I need a different APN for 5G on H2O?

No. The same APN handles 4G LTE and 5G on AT&T's network. To get 5G specifically, enable 5G in network mode settings and confirm your plan includes 5G access.

Why is the H2O APN att.mvno and not just att?

AT&T uses the .mvno suffix to distinguish wholesale MVNO traffic from postpaid customers. The naming tells AT&T's network the connecting line is on a third-party MVNO plan, not direct AT&T. H2O is one of several MVNOs that uses this APN value.

My APN screen is grayed out on my iPhone. What do I do?

Locked iPhones from another carrier often refuse APN editing. Request an unlock from the original carrier first. If the iPhone is already unlocked, run Reset Network Settings and reinstall the H2O profile through carrier provisioning.

Can I use my H2O SIM in an unlocked AT&T-postpaid phone?

Yes, as long as the phone is genuinely unlocked. H2O uses the same network bands and frequencies as AT&T postpaid, so any unlocked AT&T-compatible phone should work. The APN values are different from postpaid; use the H2O values listed above.

What does MMS Max Message Size 1048576 mean?

It is the MMS attachment size cap in bytes (exactly 1 MB), the standard across US carriers including H2O Wireless. Files larger than 1 MB should go through iMessage or Wi-Fi-based messaging instead.