iphone 4s celular network issue

Howdy shoerofi,

If I understand correctly your phone is not consistently staying connected to your cellular service unless you restart it, which seems to fix it for a bit. I would use the rest of the troubleshooting steps from the following article:

If you see No Service in the status bar of your iPhone or iPad

1. Remove the SIM card. If the SIM card is damaged, worn, or bent, or if it's too big or small for the SIM tray, contact your carrier for a new one. Then reinsert the SIM card.
2. Check for a carrier-settings update: Connect to a Wi-Fi network, tap Settings > General > About, and install any available carrier-settings updates. If you can't connect to Wi-Fi, connect your device to a computer that has iTunes.
3. Update your iPhone to the latest version of iOS.
4. Reset network settings by tapping Settings > General > Reset > Reset Network Settings. This will reset all network settings, including Bluetooth pairing records, Wi-Fi passwords, VPN, and APN settings.
5. Contact your carrier to check for any network or account issues.
6. Restore your iPhone.

Thank you for using Apple Support Communities.

All the very best,

Sterling

Wonderful! Thanks for the update, glad to know your connection is solid now.