Debbra Wetteroth (Saint Louis MO) is security manager for SBC Telecom's Information Services Department. Before joining the IS group, she spent 15 years in Central Office Engineering for a major telephone company. Debbra holds seven certifications in telecom engineering.

• 1. Introduction 2. Overview of the OSI Reference Model and its Traditional Applications 3. Numbering Systems 4. Transmission Fundamentals 5. Physical Layer Interface 6. Error Control 7. Data Link Layer Interfaces 8. Networking Layer Interfaces 9. Transport through Application Interfaces 10. Analog to Digital Evolutions 11. Security Layer by Layer 12. Glossary

Debbra Wetteroth (Saint Louis MO) is security manager for SBC Telecom's Information Services Department. Before joining the IS group, she spent 15 years in Central Office Engineering for a major telephone company. Debbra holds seven certifications in telecom engineering.

• 1. Introduction 2. Overview of the OSI Reference Model and its Traditional Applications 3. Numbering Systems 4. Transmission Fundamentals 5. Physical Layer Interface 6. Error Control 7. Data Link Layer Interfaces 8. Networking Layer Interfaces 9. Transport through Application Interfaces 10. Analog to Digital Evolutions 11. Security Layer by Layer 12. Glossary