What is request number?

When you submitted an unlock request your carrier probably sent you and email confirming it. The request number would be in that email. It may have also been displayed on the confirmation screen if you requested the unlock online, or told to you over the phone if you called in the unlock request. And the request number is not required to unlock the phone, its only purpose is to provide a means of tracking the request if you contact the carrier again. Here is some information that may be helpful-->How to unlock your iPhone for use with a different carrier - Apple Support

Whatever it is, the matter is with the carrier that owns the SIM lock. Apple can't do anything to help.

You have to call the service provider that your device is locked to.

Borrow a friends phone for a few minutes.

Please see this document for details on how to unlock your phone: https://support.apple.com/en-us/HT201328