STM-1 has been patched between Huawei and Other vendor's equipment in order to perform connectivity between other vendor's Equipment and MSC A.Made cross connection at VC12 level on that STM-1 after testing Muting and Echo occurs at all the voice channels.
Disconnect teh port at Huawei Optical port and again tested at other vendor's side PCM remains enable and voice channels goes down. The main of the PCM enable could be
1. Cross patching occurs between Huawei and Other Vendor's Equipment.
2. Diagnostic Loop back at either side of the connectivity.
Check all the Loop back conditions at the Huawei end and no such behaviuor observed then it was found that the ECHO and MUTING at the voice channels was due to the DISGNOSTIC LOOP BACK at the other vendor's equipment side.
STM-1 patched between Huawei and other vendor's Equipment and service configuration has been carried out and tested for voice calls then Muting and Echo at all the traffic/voice channels occured.
Disable all the cross connections but the PCM remains enable and channels of SDH tributary goes down which should not be the case.
Disconnect the port at other vendor's equipment then PCM and Channels goes down.
Same behaviour with the LASER SHUT DOWN occurs.
After the physical connectivity of Optical/Electrical ports must check the Default/ Diagnostic Loop back condition in order to avoid MUTING and ECHO at the Voice Channels