ADTRAN H4TU-R Card
Normal Status Lights
                
                    
                        Light
                     | 
                    
                        STATUS
                     | 
                    
                        Description & Suggested Action
                     | 
                
| DSL1/DSL2 | Unlit | No sync // Call your Carrier. | 
Red | Poor signal quality // Call your Carrier. | Yellow | Marginal signal quality // Call your Carrier. | RED - Flashing | Error detected on HTU-C or HTU-R // Call your Carrier. | | DS1 | Unlit | Premise equipment T1 signal not present or wrong format // Call your Vendor. | 
RED - Flashing | Premise equipment T1 signal errors // Call your Vendor. | | ALM | Red  | Local alarm at HTU-R Card detected. | 
Yellow | Remote alarm at HTU-C Card detected. | | ESF/SF | Unlit | Unframed mode // Call your Carrier. | 
Yellow | ESF Framing | Green | SF Framing | | B8ZS/AMI | Yellow | B8ZS | 
Green | AMI | | LBK | Yellow | Active local loop back at the HTU-R. | 
                
        For more information or to have your device listed please contact
            
            Infotel Systems
        
        The Story Behind "Status Lights"