One of the most annoying issues reported by many iPhone users is No service. If you see “No service” in the upper-right corner of the phone’s screen, it means that you can’t place or receive calls and send and receive SMS and MMS. There are many things you can do to fix this, and we are going to share 5 ways to fix iPhone 4/5/6 no service problem and some additional solutions that can help you get rid of the issue.
Before you start with the solutions, contact your carrier to make sure that your account is active.
5 ways to fix iPhone 4/5/6 no service problem

Solution No.1: Airplane mode
This is one of the tricks that can fix the problem. Navigate to Settings, enable the Airplane mode, wait for a couple of seconds and then turn the Airplane mode off. Many users reported that after doing this, No service message disappeared.

Solution No.2: Make sure that Cellular data is enabled
To do this, head to Settings > Cellular and if Cellular data is set Off, turn it On.

Solution No.3: Restart your iPhone
To restart your iPhone, press and hold the sleep/wake button, and then drag the slide to turn your phone off. Press and hold the sleep/wake button and turn your iPhone back on.

Solution No.4: Update carrier settings
You can fix the problem by updating the carrier settings. It is a very simple thing to do. Just go to Settings > General > About. If the update is available, you will be asked if you would like to update the carrier settings now – tap Update.

Solution No.5: Reset network settings
Whenever you have Wi-Fi or cellular issues with your iPhone, reset network settings is usually listed as one of the solutions. This option will reset cellular settings, Wi-Fi settings, VPN and APN settings to factory defaults. Follow these steps:
- Go to Settings
- Tap General
- Tap Reset
- Tap Reset network settings

What else?
Most users who experienced this issue were able to solve it with one of 5 ways to fix iPhone 4/5/6 no service problem. If you tried all the above-mentioned solutions but you still see No service in the upper right corner of the screen, see the solutions below.
Re-insert your SIM card
Take your SIM card out and place it back in. If you notice any damages on the SIM card, make sure to contact your carrier and ask for a SIM card replacement.
Update iOS
Update your device to the latest version of iOS. Here is what you need to do:
- Connect your iPhone to a power source
- Connect to a Wi-Fi network
- Head to Settings > General > Software Update
- If there is a new version, tap Download and Install.
Reset all settings
Another thing you can do is to reset all settings. Your data and apps will not be deleted.
- Go to Settings
- Tap General
- Tap Reset
- Tap Reset all settings
Hello i am having iphone 4 , using reliance GSM connection , its frequently loosing signal and shows no service.
also
when reset sometimes it works for 30-60 min but after that again no
service, also when rebooted it some times stuck on apple logo 4-5 times
i already tried following option
1 n/w reset
2 reset all content and setting.
3. restore from itune.
4, airplane mode on /off
4.with another sim card
5. dfu mode / hard reboot.
Iphone 4 having no service even after no sim installed
please help if anyone has the solution
IC change it
Hello i am having iphone 4 , using reliance GSM connection , its frequently loosing signal and shows no service.
also
when reset sometimes it works for 30-60 min but after that again no
service, also when rebooted it some times stuck on apple logo 4-5 times
i already tried following option
1 n/w reset
2 reset all content and setting.
3. restore from itune.
4, airplane mode on /off
4.with another sim card
5. dfu mode / hard reboot.
Iphone 4 having no service even after no sim installed
please help if anyone has the solution