I configured both ports of a Cisco ATA 186 connected to CM 4.1. On both ports I've configured Analogue telephones. The telephone working on the 1st port works fine, but the phone connected to 2nd port will ring once and the connection is broken. If I change the ports then, the phone on the first port will work fine but the phone connected to the 2nd port got the same issue.
I hope someone can help me sort out this issue.