We have an SL1100 with a PRI circuit from Optimum (cable company). Incoming and outgoing calls on digital phones are fine. Outgoing calls using an analog station result in massive echo on the called party side (recipient). The echo occurs for all outside parties. No echo on the inside party. No echo on internal calls.

We have adjusted 10-03 SLI DB Trans and Rec and 14-01 Trunk settings transmit and receive. We also adjusted the cable length in 10-03-06 to Level 1. No improvement really only slight improvement. NTAC says the PRI is coming in TOO HOT from the telco. The telco is using a Edgewater 4550 unit to deliver the PRI but getting the telco to comprehend the problem is a bit difficult .

NEC Ntac suggests using an CSU/DSU in between the Telco and the NEC. I have Adtran ACE but I always thought they would boost the T1 signal and we want to drop the signal by -7.5db.

Am I correct about the CSU (useless)? What are you other suggestions?

This has been an ongoing issue but we always suspected an old Polycom conf rm phone was the issue but that has been replaced.

Last edited by jsaad; 11/05/18 11:52 AM.
Phone systems for NJ and NY businesses