Hello! I'm here to help you with tracking a lost phone using the SIM card number. I understand your concern about trying to locate your lost phone without success using Gmail, so you're considering using the SIM card number instead.
Unfortunately, tracking a phone using just the SIM card number is not possible. The SIM card number is primarily used to identify the subscriber's account with the mobile network operator and does not have built-in tracking capabilities like GPS or location services.
For tracking a lost phone, the most common method is using the phone's built-in features like Find My iPhone for Apple devices or Find My Device for Android devices. These services require the phone to be connected to the internet to provide real-time location data.
If you haven't already, try reaching out to your mobile network operator to see if they can assist you in locating your phone. They may be able to track the phone's last known location based on cell tower information. Additionally, you can report the loss to the local authorities, especially if you suspect it may have been stolen.
I hope this information helps, and I wish you the best of luck in locating your lost phone. If you have any more questions or need further assistance, feel free to ask.