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R26 is plugged with FXS voice unit, and the called hear nothing when picking up the phone after upgrading the release

Publication Date:  2012-07-27 Views:  251 Downloads:  0
Issue Description

Networking diagram: telephone 1---R26 router 1 (FXS module) ---IP---2R6 router 2 (FXS module) ---telephone 2

Originally, bother routers were of Release VRP1.6, and the calling and answer were normal. Once the router 1 is upgraded to Release 1.74-0108, no audio could be heard when hooking off if telephone 1 is called.

Alarm Information

Handling Process
The problem could be solved by changing the descriptor string of H.323 voice in Release 1.74. Configure the following command in voice view:

voip h323-descriptor Standard Gateway


Root Cause

 The problem arises from diversity of H.323 descriptors in different versions.

H.323 descriptor is used to distinguish if the equipment used in H.323 call is from Huawei; if so, the equipment will open the logic channel once TCS ACK is received, or it will not open the channel until MSD request is received. In case the equipments from Huawei intercommunicate with each other, and the default descriptors of H323 at both sides are different, the process to establish a session will have to be in waiting for MSD; additionally, Huawei’s equipments will not initiate MSD request, and the logic channel will not be opened, resulting in that no audio is received after hooking-off.

In the development of VRP version, the default value of H323 is changed many times due to various reasons, including “Huawei Gateway”, “Standard Gateway”, “Vrp Gateway”, “Default Gateway”, etc.

The descriptor of VRP 1.74-0108 is defaulted to “Vrp Gateway”, and that of VRP 1.6 is defaulted to “Standard Gateway, so the problem occurs.