part of old message gets clubbed with part of new message and reflects on screen

On two different dates, a handset received two separate A2P

SMS messages, each consisting of two parts:

1. On 15th July, a two-part message was delivered and

correctly displayed as a single combined message.

2. On 18th July, a different two-part message was again delivered and correctly

displayed as expected.

However, in addition to these two correctly displayed messages, the handset

unexpectedly displayed a third message. This third message was a combination of

Part 1 of the 15th July message and Part 2 of the 18th July message, leading to

message content corruption and user confusion.

Preliminary Technical Analysis:

All four SMS parts contained User Data Headers (UDH) for

message concatenation.

It was observed that the Message Reference ID in the UDH was the same across

both messages (i.e., same reference number used for both the 15th and 18th July

messages).

The handset appears to have used the matching Message Reference ID to combine

SMS parts, without validating timestamps or delivery context.

This led to incorrect concatenation across two unrelated messages delivered on

different days.