Overview

SMS FWL changes the TP-More-Messages-to-Send (TP-MMS) value from "More messages are waiting for the MS in this SC" to "No more messages are waiting for the MS in this SC". As a result, the terminating MSC replies with TCAP END instead on TCAP CONTINUE causing the CONCAT SMS to fail since succeeding SMS will no longer be delivered by the foreign SMSC.

Solution

This issue happened very rarely in the past, making it difficult to determine the pattern. However, in all the past cases the root cause was not particularly on Lithium, but was the lack of optimized screening function on the STP side that does not forward the TCAP-Begin from the SMSC to the Firewall.

Based on STP vendors and their implementation of screening for MT, three classes of MAP Screening implementations exist. The table below lists the characteristics of these classes (please note that this classification is not defined as an official specification, it is rather based on observation of our install base and understanding of various STP implementations):

If your MAP screening is not classified as C, contact your STP vendor to discuss possible solutions to optimize MAP screening functions.

If you still encounter problems even though your MAP screening is optimized, please contact support providing below details:

• If the issue is happening for only 1 network or all
• If the issue intercepted MT messages
• If the issue is for Inbound Roamer from Foreign Network, roaming in Smart
• tp_walkall from the node where this message was handled
• Message logs from the FWL for the faulty transaction
• PCAP trace run on the FWL nodes when performing a test message (can be obtained by following the steps defined in this article)