Fail to Make Calls Outgoing Calls to Bell PBX

Publication Date:  2015-07-24 Views:  297 Downloads:  0
Issue Description
Version: U1980 V100R001C01SPC700

Network:

Bell PBX
/ (prefix 0)
(TUP)
/
U1980–(TUP)–CC08B
\
(TUP)
\ (prefixes 1, 2, 4, and so forth)

Private network

After replacing with a CC08, U1980 users dial prefix 1, 2, or 4, outgoing calls can be routed to the private network properly. However, outgoing calls cannot be routed to Bell PBX properly. After the number is dialed, the busy tone is heard.
Handling Process
Step 1 Use the LMT to trace TUP messages. For calls routed to Bell PBX, when the peer end receives the IAI message, the peer end returns the CFL message to directly release the call even when the U1980 is reporting digits one by one, as shown in the following figure.



Since services run properly before the original CC08 is replaced by the U1980, it is suspected that the IAI message sent by the U1980 is different from the IAI message sent by the CC08.

Step 2 Compare the IAI message sent by the U1980 with the IAI message sent by the CC08. Two differences are found. One is that the orders of the calling and called numbers are different in the IAI messages. The other is that the echo suppression indicator field in the IAI message sent by the CC08 indicates that the outgoing echo suppression is not contained while the same indicator in the IAI message sent by the U1980 indicates that the outgoing echo suppression is contained.

Step 3 Confirm with the CC08 R&D personnel. The different orders of the calling and called numbers are caused by the parsing tool. The orders are the same in fact.

The preliminary judgment is as follows: Due to special settings, Bell PBX does not support the echo suppression indicator value indicating that the outgoing echo suppression is contained.

Step 4 Run the config protocol tup officeno 7 servicecontrol 100 command to forcibly disable the echo suppression function. The fault is rectified.

NOTE:
To restore the default setting, run the config protocol tup officeno 7 servicecontrol 0 command.

Some indicators in the IAI message obtained after the modification are as follows:
Initial address message with additional information


00100001 H1H0: IAI
--011000 calling user type: common user, which is used among city offices
00------ reserved: 0x0
Message indicators
------00 address type indicator: user number
----00-- circuit type indicator: no satellite circuit in connection
--00---- continuity check indicator: continuity check not required
-0------ echo suppression indicator: outgoing echo suppression not contained
0------- international incoming call indicator: not international incoming call
-------0 redirecting call indicator: not redirecting call
------0- indicator about whether all digital paths are required: common call
-----1-- signal path indicator: all SS7 system paths
----0--- reserved: 0x0
0110---- address signal number: 0x6
----0001 address signaling: digit 1

----End
Root Cause
Bell PBX is incompatible with the U1980.
Suggestions
 Generally, rectify a fault based on the rule that the side disconnecting the call should locate the fault. Ask the peer end to give the specific cause, and modify configurations on the local end. This is a faster method. In this office, Bell device is an old device that has been used for more than 20 years. No maintenance engineer is available. As a result, the fault can be located only through repeated comparison.

 When encountering faults about interworking with old Bell devices, pay attention to the echo suppression indicator field. Generally, this field will not affect calls.

END