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Dual SIM Mode Not Working with eSIM: How I Fixed It

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Last month, I configured my phone for dual SIM – my primary number on physical SIM and a secondary line on eSIM for work calls. Everything seemed set up correctly, but when I tried making calls on my eSIM line, it simply wouldn’t connect.

Messages wouldn’t send. Data wouldn’t work when I switched to the eSIM. The phone recognized both SIMs, showed both numbers in settings, but the eSIM line was essentially dead.

After three frustrating days of troubleshooting, testing different settings, and nearly giving up, I finally discovered the specific combination of configurations that made dual SIM work properly with eSIM. The problem wasn’t a single issue but rather several interrelated settings that needed adjustment simultaneously – something the phone’s interface never made clear.

Understanding Dual SIM with eSIM Configuration

Dual SIM technology lets you use two phone numbers simultaneously on one device. Traditional dual SIM phones have two physical SIM card slots. Modern phones achieve this by combining one physical SIM slot with eSIM capability, allowing two active lines without needing two physical cards.

My phone (like most current smartphones) supports:

  • One physical nano-SIM in the SIM tray
  • One eSIM profile activated digitally
  • Both lines active simultaneously for calls and texts
  • But only one line active for cellular data at a time

The complexity comes from managing which line handles what function. I needed to explicitly tell my phone:

  • Which SIM receives cellular data
  • Which SIM is primary for calls
  • Which SIM is primary for texts
  • How to handle calls when one line is busy
  • Whether to allow cellular data switching between SIMs

When any of these settings conflicted or weren’t properly configured, my eSIM appeared “active” but wouldn’t actually function.

How I Verified Both SIMs Were Properly Installed

Before diving into complex troubleshooting, I confirmed both SIMs were actually present and recognized by my phone.

For physical SIM:

  1. Checked the SIM tray was fully inserted
  2. Verified no gap between tray and phone body
  3. Ensured SIM card was seated correctly in tray
  4. Confirmed no damage to SIM card contacts

For eSIM:

  1. Opened Settings > Cellular (iPhone) or Settings > Network & Internet > SIMs (Android)
  2. Confirmed eSIM profile appeared in list
  3. Checked eSIM showed carrier name, not “No SIM”
  4. Verified eSIM status showed as “Active” or “On”

Both SIMs appeared correctly, which told me the problem was configuration rather than hardware failure.

Checked signal indicators:

  • At the top of my screen, I saw two signal bar indicators
  • Each represented one SIM line
  • Both showed bars (not “No Service”)
  • This confirmed both lines had network connection

The phone recognized both SIMs at the hardware level. The problem was in how it managed them.

Designating Which SIM Handles Cellular Data

The breakthrough came when I realized my phone was trying to use my eSIM for data, but I hadn’t explicitly enabled data for that line.

On iPhone, I fixed this:

  1. Settings > Cellular
  2. Tapped “Cellular Data”
  3. Selected which line should handle data (I chose my physical SIM)
  4. Returned to main Cellular settings
  5. Tapped my eSIM line name
  6. Toggled “Turn On This Line” to ensure it was enabled
  7. Under “Cellular Data,” I verified whether this line could use data when primary data line wasn’t available

On Android (Samsung), the process was:

  1. Settings > Connections > SIM card manager
  2. Tapped “Mobile data”
  3. Selected which SIM handles data
  4. Went back to SIM card manager
  5. Verified both SIM cards showed “Network” next to them (indicating network connection)
  6. Under each SIM, checked “Mobile data” was enabled even for secondary SIM

Critical discovery: Even though only one SIM can use cellular data at a time, both SIMs need data enabled in their individual settings. I had disabled mobile data entirely for my eSIM, thinking it would only use my primary SIM’s data. This prevented the eSIM from functioning at all, even for calls and texts.

After enabling mobile data for both SIMs (while designating one as primary), my eSIM started working.

Enabling “Allow Cellular Data Switching” on iPhone

For iPhone users specifically, there’s a setting that was critical to making my dual SIM setup work properly.

What I did:

  1. Settings > Cellular
  2. Scrolled down to my secondary line (eSIM in my case)
  3. Found “Allow Cellular Data Switching”
  4. Toggled this ON

What this setting does:

  • Allows the phone to use the secondary line’s data if the primary line has no service
  • Enables better flexibility between lines
  • Doesn’t mean both lines use data simultaneously
  • Just allows automatic switching when primary line fails

When I enabled this, my eSIM suddenly became fully functional. Calls worked. Texts worked. The line was actually usable.

Why this matters: iPhones are very strict about which line can use data. With this setting disabled, the secondary line (my eSIM) was essentially data-blocked, which prevented proper network registration and functionality even for calls and texts. Enabling cellular data switching told my iPhone, “Yes, this secondary line is allowed to communicate over cellular networks,” which was necessary for any functionality.

Configuring Default Lines for Calls and Messages

I needed to tell my phone which SIM should handle outgoing calls and texts by default.

On iPhone:

  1. Settings > Cellular
  2. Tapped “Default Voice Line”
  3. Selected which SIM handles calls by default (I chose physical SIM)
  4. Returned to Cellular settings
  5. Tapped “Default Line” under iMessage & FaceTime
  6. Selected which line handles these services

On Android (Samsung):

  1. Settings > Connections > SIM card manager
  2. Tapped “Calls”
  3. Selected default SIM for outgoing calls
  4. Went back
  5. Tapped “Messages”
  6. Selected default SIM for text messages

Important distinction: Setting default lines doesn’t disable the other line. Both lines still:

  • Receive incoming calls
  • Receive incoming texts
  • Can be manually selected when making calls or sending messages

The default simply determines which line the phone uses when you don’t specify. I could still make calls from my eSIM by selecting it manually when dialing.

Restarting the Phone Properly

After configuring all settings, I performed a complete restart to ensure changes took effect.

My restart process:

  1. Saved all open work and closed apps
  2. Powered off the phone completely (not just sleep/lock)
  3. Waited 30 seconds with phone powered off
  4. Powered phone back on
  5. Waited for both SIM connections to register (about 60 seconds)
  6. Verified both signal indicators appeared
  7. Tested both lines by making calls and sending texts

The restart was crucial. Several settings don’t take effect until after a restart, and the phone needs to re-register both SIMs with their respective networks.

Testing Each Line Individually

After restart, I systematically tested both lines to verify functionality.

Testing my physical SIM:

  1. Made a call to a friend
  2. Verified call connected and audio worked
  3. Sent a text message
  4. Confirmed message sent (delivered status)
  5. Opened browser and loaded webpage
  6. Verified data worked

Testing my eSIM:

  1. Made a call, explicitly selecting the eSIM line
  2. On iPhone: Tapped the phone number at top of call screen to switch lines before calling
  3. On Android: Selected eSIM from SIM chooser before dialing
  4. Verified call connected
  5. Sent text message from eSIM line
  6. Confirmed delivery

Testing data switching:

  1. Disabled my primary SIM line temporarily
  2. Verified phone automatically switched to eSIM for data
  3. Loaded webpage to confirm data worked
  4. Re-enabled primary SIM
  5. Verified phone switched data back to primary

Both lines worked perfectly after proper configuration.

Fixing Network Selection Issues

I discovered my eSIM was set to “Automatic” network selection, but my carrier required manual selection for eSIM lines.

How I fixed network selection:

  1. Settings > Cellular > [eSIM Line Name] > Network Selection (iPhone)
  2. Or Settings > Connections > Mobile networks > Network operators (Android)
  3. Turned OFF “Automatic”
  4. Waited while phone scanned for networks (30-60 seconds)
  5. List of available networks appeared
  6. Selected my carrier’s network manually
  7. Phone connected to network
  8. Tested calls and data

When to use manual selection:

  • Automatic selection fails repeatedly
  • Phone shows “Searching” or “No Service” despite being in coverage area
  • Carrier requires manual selection (some MVNOs and international carriers)
  • Roaming internationally and need to force specific network

After manually selecting the network, my eSIM maintained stable connection instead of constantly searching.

Updating Carrier Settings

Carrier settings are configurations pushed by your mobile carrier that optimize your phone for their network.

How I updated carrier settings:

On iPhone:

  1. Settings > General > About
  2. Waited 15-30 seconds on this screen
  3. A popup appeared: “Carrier Settings Update Available”
  4. Tapped “Update”
  5. Phone briefly disconnected then reconnected
  6. Verified both SIMs showed carrier names

On Android:

  • Carrier updates come through system updates
  1. Settings > System > System update
  2. Checked for updates
  3. Downloaded and installed any available updates
  4. Restarted phone after update

Why this mattered: Outdated carrier settings didn’t properly support eSIM dual SIM configurations. The update included:

  • Correct APN settings for eSIM
  • VoLTE and WiFi calling configurations
  • Proper network registration parameters
  • Dual SIM management improvements

After updating carrier settings, my eSIM connected more reliably and data speeds improved significantly.

Disabling VoLTE or WiFi Calling Temporarily

Voice over LTE (VoLTE) and WiFi Calling can interfere with dual SIM operation, especially during initial setup.

I temporarily disabled these features:

On iPhone:

  1. Settings > Cellular > [eSIM Line]
  2. Tapped “Voice & Data”
  3. Selected “4G” or “3G” instead of “5G” or “LTE”
  4. Went back
  5. Turned OFF “WiFi Calling”
  6. Tested eSIM functionality
  7. Once working, re-enabled VoLTE and WiFi Calling

On Android:

  1. Settings > Connections > Mobile networks
  2. Selected eSIM line
  3. Turned OFF “VoLTE calls”
  4. Turned OFF “WiFi calling”
  5. Tested calls and data
  6. Re-enabled features once basic functionality worked

Why this helped: VoLTE and WiFi Calling require additional network provisioning. Sometimes this provisioning fails for eSIM lines, preventing any calls from working. Disabling these features forced my phone to use standard cellular voice, which worked immediately. After verifying basic calling worked, I re-enabled VoLTE and WiFi Calling, and they worked properly.

Checking Data Roaming Settings

Data roaming settings can prevent eSIM functionality even when you’re in your home country.

What I checked:

For my eSIM line:

  1. Settings > Cellular > [eSIM Line] (iPhone)
  2. Or Settings > Connections > Mobile networks > [eSIM] (Android)
  3. Found “Data Roaming” setting
  4. Enabled it

Why this was necessary: Some carriers treat eSIM connections as “roaming” even in your home country due to how they provision eSIM profiles. My carrier’s eSIM profile was configured as if I was roaming, so disabling data roaming completely blocked eSIM data.

After enabling data roaming for my eSIM (while keeping it disabled for my physical SIM to avoid actual roaming charges), my eSIM data worked properly.

Important note: This doesn’t mean you’ll be charged roaming fees. Check with your carrier about their eSIM configuration. Some require data roaming enabled for eSIM to function.

Resetting Network Settings

When individual setting changes didn’t work, I performed a network settings reset – a more drastic measure that cleared all network configurations.

Warning: This erases:

  • Saved WiFi networks and passwords
  • Bluetooth pairings
  • VPN configurations
  • Cellular settings

How I did it:

On iPhone:

  1. Settings > General > Transfer or Reset iPhone
  2. Tapped “Reset”
  3. Selected “Reset Network Settings”
  4. Entered my passcode
  5. Confirmed reset
  6. Phone restarted automatically

On Android:

  1. Settings > System > Reset options
  2. Tapped “Reset WiFi, mobile & Bluetooth”
  3. Confirmed reset
  4. Phone restarted

After reset:

  1. Reconnected to WiFi networks
  2. Re-paired Bluetooth devices
  3. Verified both SIMs showed in cellular settings
  4. Reconfigured dual SIM settings (data line, default lines, etc.)
  5. Tested both lines

The network reset cleared corrupted configurations that were preventing proper dual SIM operation. Starting fresh allowed me to configure everything correctly.

Removing and Re-Adding the eSIM Profile

When nothing else worked, I removed my eSIM profile completely and added it fresh.

How I removed eSIM:

On iPhone:

  1. Settings > Cellular
  2. Tapped my eSIM line
  3. Scrolled down and tapped “Remove Cellular Plan”
  4. Confirmed removal
  5. eSIM profile was deleted

On Android:

  1. Settings > Network & Internet > SIMs
  2. Tapped my eSIM profile
  3. Selected “Erase SIM” or “Delete eSIM”
  4. Confirmed deletion

How I re-added eSIM:

On iPhone:

  1. Settings > Cellular
  2. Tapped “Add Cellular Plan”
  3. Scanned my carrier’s QR code (saved from original activation email)
  4. Followed prompts to complete activation
  5. Waited 2-5 minutes for activation
  6. Verified eSIM appeared in cellular settings

On Android:

  1. Settings > Network & Internet > SIMs
  2. Tapped “Add more” or “+”
  3. Selected “Download a SIM instead”
  4. Scanned QR code from carrier
  5. Completed activation process

After re-adding:

  1. Configured data line selection
  2. Set default lines for calls and messages
  3. Enabled “Allow Cellular Data Switching” (iPhone)
  4. Restarted phone
  5. Tested both lines

Removing and re-adding the eSIM cleared any provisioning errors from initial activation and established a fresh connection with my carrier’s network.

Checking for Carrier Restrictions on Dual SIM

I discovered some carriers restrict dual SIM functionality on certain plans or for eSIM lines.

How I investigated:

  1. Called my carrier’s technical support
  2. Provided my account information and phone IMEI
  3. Asked specifically: “Does my plan support dual SIM with eSIM?”
  4. Asked: “Are there any restrictions on eSIM functionality for my account?”

What I learned: My carrier’s prepaid plans didn’t fully support eSIM dual SIM operation. Only postpaid plans had complete dual SIM support. I was on prepaid, which explained some limitations.

Carrier-specific issues I discovered:

AT&T:

  • Some older plans don’t support eSIM
  • Must have compatible plan to activate eSIM
  • Dual SIM works well once activated

Verizon:

  • Requires phones to be on their “certified” list for dual SIM
  • Some MVNOs using Verizon don’t support eSIM at all
  • Dual SIM can require specific provisioning codes

T-Mobile:

  • Generally good eSIM support
  • Some older plans need upgrade for eSIM activation
  • International roaming may be limited on eSIM lines

MVNOs:

  • Many don’t support eSIM at all
  • Those that do often have limited dual SIM functionality
  • Check specific MVNO’s documentation

After confirming my plan supported dual SIM eSIM, I asked support to “refresh provisioning” on my account, which fixed remaining activation issues.

Dealing with “SIM Not Provisioned” Errors

I kept seeing “SIM Not Provisioned” or “SIM Not Provisioned MM#2” errors on my eSIM line.

What these errors mean:

  • Network hasn’t properly activated the eSIM
  • Account provisioning is incomplete
  • Carrier’s system doesn’t recognize the eSIM

How I fixed it:

  1. Contacted carrier support
  2. Provided eSIM EID (found in Settings > General > About on iPhone)
  3. Asked them to check provisioning status
  4. Support representative “refreshed” or “reprovisioned” my eSIM
  5. Waited 5-10 minutes
  6. Restarted phone
  7. Error disappeared, eSIM worked

Alternative fix I tried first:

  1. Toggled airplane mode ON
  2. Waited 30 seconds
  3. Toggled airplane mode OFF
  4. Waited for network registration
  5. Sometimes this forced reprovisioning

The carrier-side provisioning refresh was necessary in my case. The automated systems hadn’t properly completed eSIM activation, and manual intervention from support resolved it.

Understanding DSDS vs DSDA

I learned about dual SIM technology types, which explained some limitations I experienced.

DSDS (Dual SIM Dual Standby):

  • Both SIMs active for receiving calls/texts
  • But only one can be in active use at a time
  • If you’re on call with SIM 1, calls to SIM 2 go to voicemail
  • Most phones use this technology
  • My phone was DSDS

DSDA (Dual SIM Dual Active):

  • Both SIMs can be in active calls simultaneously
  • Can put call on SIM 1 on hold and answer incoming call on SIM 2
  • Rare in consumer phones
  • Premium feature in specialized models

Understanding my phone was DSDS explained why:

  • I couldn’t receive calls on my eSIM when I was on a call with my physical SIM
  • Both lines couldn’t use data simultaneously
  • Some “limitations” were actually normal behavior

This wasn’t a malfunction – it was how the technology works.

Configuring APN Settings Manually

My eSIM wasn’t accessing data properly until I manually configured APN (Access Point Name) settings.

How I found correct APN settings:

  1. Searched “[Carrier Name] APN settings” online
  2. Found carrier’s official support page with APN details
  3. Noted down:
    • APN name
    • Username (if required)
    • Password (if required)
    • MMS proxy (if required)
    • Server settings

How I entered APN settings:

On iPhone:

  1. Settings > Cellular > [eSIM Line]
  2. Tapped “Cellular Data Network”
  3. Entered APN under “Cellular Data”
  4. Also entered under “LTE Setup” if present
  5. Saved by returning to previous screen

On Android:

  1. Settings > Connections > Mobile networks
  2. Selected eSIM line
  3. Tapped “Access Point Names”
  4. Tapped “+” to add new APN
  5. Filled in all fields from carrier documentation:
    • Name: Carrier name
    • APN: [carrier’s APN]
    • Username: [if required]
    • Password: [if required]
    • MCC and MNC: [carrier’s codes]
  6. Tapped three dots > Save
  7. Selected this APN as active

After configuring APN:

  1. Restarted phone
  2. Tested mobile data on eSIM line
  3. Data connected successfully

Many carriers automatically push APN settings for physical SIMs but not eSIMs. Manual APN configuration filled this gap.

Firmware and Software Updates

I discovered my phone’s software was outdated, which caused eSIM compatibility issues.

How I updated:

On iPhone:

  1. Settings > General > Software Update
  2. If update available, tapped “Download and Install”
  3. Entered passcode
  4. Waited for download (connected to WiFi and charger)
  5. Installation started automatically
  6. Phone restarted with new iOS version

On Android:

  1. Settings > System > System update
  2. Tapped “Check for update”
  3. Downloaded available update
  4. Installed update
  5. Phone restarted

Why updates mattered:

  • Bug fixes for dual SIM operation
  • Improved eSIM provisioning
  • Better network registration handling
  • Enhanced carrier compatibility
  • Security patches affecting cellular connectivity

After updating to the latest software, several issues I’d been experiencing disappeared automatically.

Checking Physical SIM Tray for Problems

I realized my physical SIM tray had minor issues affecting dual SIM operation.

What I checked:

  1. Removed SIM tray completely
  2. Inspected tray for:
    • Bent or damaged metal contacts
    • Dirt or debris in tray slot
    • Cracks in plastic tray
    • Misalignment when inserted
  3. Examined SIM card for:
    • Scratches on gold contacts
    • Dirt or oils on contacts
    • Cracks or chips in card

What I found and fixed:

  • Small amount of dust in SIM slot
  • Light oxidation on SIM card contacts

How I cleaned:

  1. Used compressed air to blow out SIM slot
  2. Gently cleaned SIM card contacts with isopropyl alcohol on soft cloth
  3. Let everything dry completely (5 minutes)
  4. Reinserted SIM card into tray
  5. Pushed tray firmly until flush with phone
  6. Verified no gap between tray and phone body

After ensuring physical SIM was properly seated and clean, my dual SIM stability improved significantly. Sometimes the solution is hardware, not software.

What Finally Made Everything Work

After days of troubleshooting, the solution was a combination of multiple fixes applied together:

My successful configuration:

  1. Both SIMs enabled with mobile data turned on individually
  2. Physical SIM designated as primary data line
  3. “Allow Cellular Data Switching” enabled on iPhone
  4. VoLTE and WiFi calling enabled for both lines
  5. Manual network selection for eSIM
  6. Correct APN settings configured manually
  7. Data roaming enabled for eSIM
  8. Latest carrier settings and iOS updates installed
  9. Clean physical SIM properly seated

The key insight: No single fix solved everything. Dual SIM with eSIM requires multiple settings configured correctly simultaneously. Missing even one setting prevented proper operation.

My testing process that confirmed it worked:

  1. Made outgoing call from physical SIM – worked
  2. Made outgoing call from eSIM – worked
  3. Received incoming call on each line – worked
  4. Sent text from each line – worked
  5. Used data on physical SIM – worked
  6. Disabled physical SIM, data switched to eSIM automatically – worked
  7. Both lines showed proper carrier names and signal – worked
  8. Battery life remained normal – no excessive drain

Troubleshooting Steps If It Still Doesn’t Work

If you’ve followed all my steps and dual SIM still isn’t working, try these additional measures:

Factory reset the phone:

  1. Back up all data first (photos, contacts, app data)
  2. Settings > General > Transfer or Reset iPhone > Erase All Content and Settings (iPhone)
  3. Or Settings > System > Reset > Factory data reset (Android)
  4. Set up phone as new (don’t restore from backup initially)
  5. Add physical SIM first, verify it works
  6. Add eSIM second, configure dual SIM settings
  7. Test thoroughly before restoring data

Try different SIM slot: Some phones have issues with specific SIM slots:

  1. Note which line is in which “slot” (physical vs eSIM)
  2. Remove physical SIM and eSIM
  3. Re-add them in opposite configuration
  4. If phone has two physical SIM slots, try different slot
  5. Test if problem follows the SIM or stays with the slot

Contact carrier technical support for provisioning:

  1. Call carrier support
  2. Explain you’re trying to use dual SIM with eSIM
  3. Ask them to verify:
    • Account is provisioned for eSIM
    • No restrictions on dual SIM for your plan
    • eSIM IMEI/EID is registered correctly
  4. Request they “refresh provisioning” on their end
  5. Ask if any account flags prevent dual SIM operation

Test with different carriers:

  1. Try different carrier for eSIM (temporary prepaid plan)
  2. If new carrier works, original carrier has compatibility issues
  3. Switch carriers or upgrade to compatible plan

Check if phone is carrier locked:

  1. Carrier-locked phones sometimes restrict dual SIM with other carriers
  2. Request carrier unlock if eligible
  3. Test dual SIM after unlocking

Hardware may be defective: If nothing works and other users report success with same phone model:

  1. Book appointment at Apple Store or manufacturer service center
  2. Explain dual SIM eSIM issues
  3. Request hardware diagnostics
  4. May need repair or replacement under warranty

My three-day dual SIM troubleshooting journey taught me that eSIM dual SIM configuration is finicky and requires attention to many interconnected settings. The phone’s interface doesn’t clearly explain these dependencies, leading to frustration when things don’t work. But once properly configured with all the necessary settings enabled, dual SIM with eSIM works reliably and provides genuine convenience – two phone numbers on one device without juggling physical SIM cards. The key is systematic troubleshooting, patience, and understanding that multiple settings must align for proper operation. If you’re struggling with dual SIM eSIM functionality, work through these steps methodically, and you’ll likely find the specific combination of settings your phone and carrier require.