The ZTE C600, C620, C650, and PON GFBL, GFBH, GFBT, GFGH, GFCH, EFTL, and OLT are products designed for business communication and networking solutions. Here's a brief introduction to the key attributes of these models:

1. ZTE C600: This is a compact and cost effective device often used in small to medium sized businesses for basic telephony and data services.

2. ZTE C620: An upgrade from the C600, the C620 offers enhanced features and capabilities, making it suitable for businesses that require more advanced communication solutions.

3. ZTE C650: The C650 is a high performance model designed for larger enterprises or those with more demanding network requirements, offering robust data handling and通话能力.

4. ZTE PON GFBL: This model is part of ZTE's Passive Optical Network (PON) solutions, offering high speed data transmission and is ideal for businesses looking to upgrade their network infrastructure.

5. ZTE GFBH: This device is known for its high bandwidth and reliability, making it a popular choice for businesses that require stable and fast data services.

6. ZTE GFBT: The GFBT is designed for businesses that need to transmit large amounts of data quickly and efficiently, ensuring minimal downtime and high performance.

7. ZTE GFGH: This model is often used in environments where high data security is a priority, offering advanced encryption and protection features.

8. ZTE GFCH: The GFCH is a versatile model that can be customized to meet the specific needs of various business types, offering a balance of performance and cost effectiveness.

9. ZTE EFTL: This model is designed for businesses that require efficient and reliable data transmission over long distances, ensuring minimal signal degradation.

10. ZTE OLT: The Optical Line Terminal (OLT) is a key component in fiber optic networks, providing the interface between the service provider's network and the customer's premises.

Each of these models comes with its own set of specifications and parameters tailored to meet the unique needs of different business environments. They are designed to provide reliable, high quality communication solutions that can scale with the growth of a business. For a detailed understanding of the technical specifications, it's best to consult the official documentation or contact ZTE's customer support for the most accurate and up to date information.