Troubleshooting for Nokia 101

In two (double) SIM phone, only one SIM card can be standby/active at a time.

In dual SIM phone, both SIM cards are available at the same time when the device is not being used (so-called 'dual standby'), but while one SIM card is active, for example, making a call, sending or receiving a message, or transferring data, the other is unavailable.

Select Menu > Settings > Reset factory set. (or Restore factory set. or Restore factory settings). Enter the security code. Default security code is 12345. After that, the phone starts restoring without extra notification.

Restoring factory settings resets all settings to the default, but contacts, messages and other personal files are not affected.  
 

No. You can only change font size for messages in your device. To do so, select Menu > Messages (or Messaging) > Message settings (or More > Message settings) > Font size (or General settings > Font size).

Both SIM cards can be connected to the network at the same time, but while one SIM card is active, for example, making a call, sending or receiving a message, or transferring data, the other is unavailable.

If your device is a dual SIM device (like X1-01 and C2-00), which means both SIM cards can be connected to the network at the same time, your device has two IMEI numbers.

If your device is a two SIM device (like C1-00), which means only one SIM card can be connected to the network at a time, your device has only one IMEI number.

Only sim 1 IMEI is used to check for warranty.

Select Menu > Settings > Phone (or Phone settings or Device) > Start-up tone.
 

Select Menu > Settings > Security settings (or Security) > Access codes (or Change access codes) > Change PIN code.

Yes. To use the number screening, in another words, add a specific number as unwanted, select Menu > Messages > Message settings > Number screening (or No. screening) > Options > Add number.

The phone calls and messages from such specific number are filtered, your phone does not ring and the messages go to Screened messages folder in Menu > Messages. 

Note: The number screening is a network service. Contact your network operator or service provider for service availability and billing information.
 
 
 

No, it doesn't.  

Select Menu > Messages > Message settings > Delivery reports.