Overview

You get delivery result tcapAborted when multiple SMSes are sent from the same Sender ID ('AIC' in the example image below) for the same MSISDN, thereby leading to a high failure rate of SMS messages.

At SMSFW, you can see a high number of 'tcapAborted' errors:

You would like to know if there are any workarounds to avoid these errors, such as not rotating the virtual IMSIs on every SRI request (returning the same IMSI) or recognizing the multiple IMSIs that you returned for all SRI requests for a longer period.

Solution

It appears that Sender ID ('AIC' in the example above) is using some routing info caching to re-use the same IMSI if a message is sent to the same recipient in a short interval.

Unfortunately, from the FWL side the same scrambled IMSI cannot be used on every SRI request to the same recipient as this would weaken MT anti-spoofing capability. However, you can extend the validity of the correlation IMSI record for a longer period by adjusting the following FWL property controls the validity time of the scrambled IMSI (correlation record):

fwPropMaxIntervalBetweenSriSmAndMtFwdSm

OBJECT-TYPE
SYNTAX MtTimer
ACCESS read-write
STATUS mandatory
DESCRIPTION "Maximum time span allowed between an SendRoutingInfoForSm operation and a MtForwardSm operation. Expressed in number of seconds. Default is 60."
::= { fwProperties 21 }

To resolve this, please follow these steps:

1. Open your local MGR semi-static configuration file (common_config.txt or 'hostname'_config.txt file, in case you have alternative/additional MGR servers), found at '/usr/TextPass/etc'.
   
   
2. Find the firewallmaxintervalbetweensrismandmtfwdsm parameter and set it to 120 seconds, modifying it as follows:
   firewallmaxintervalbetweensrismandmtfwdsm="120"