Symptom
Network: IAD 132E(T)–Network device–Huawei softswitch SOFTX3000
Version: V300R001C07SPC500
Fax machines under the IAD can successfully send faxes but fail to receive faxes. The IAD is registered with the softswitch using MGCP.
Possible Cause
- The network is faulty.
- The fax mode is incorrect.
- The fax parameter is incorrectly set.
Solution
- Ask onsite engineers to check whether pack loss occurs by running the ping command. According to the onsite engineers, the network quality is good.
- Check the fax mode, and retain only transfer or T38 V3. The fault persists.
- Ask onsite engineers to capture packets. According to the packets captured onsite, at the 81th second, the IAD answers the voice call. The fax key is pressed for receiving faxes on the IAD at the 86th second, but the sender does not send any fax signals since the 88th second, resulting in the fax negotiation failure. The IAD switches to voice at the 90th second.
