VOIP, PBX & Asterisk Lessons

I am seeking a freelancer who can provide one-on-one lessons in VOIP, PBX, and Asterisk. As a beginner in this field, I am looking for guidance in setting up a PBX system, configuring Asterisk, and troubleshooting VOIP issues. The ideal freelancer should have advanced knowledge in these topics and be able to provide theory support and practical configuration instructions.