<![CDATA[Instant messaging platforms are increasingly used as notification channels for low-cost Internet Of Things security devices, yet the end-to-end latency of such channels is rarely measured and almost never decomposed into its constituent stages. This study analyses the latency and reliability of a visual notification channel that couples an ESP32-CAM module with the Telegram Bot API in a room monitoring prototype controlled by a Wemos D1 R32. An experimental quantitative approach was used. Image capture was triggered by an ultrasonic proximity threshold of 100 cm and tested at six object distances from 20 cm to 120 cm; the interval between triggering and the appearance of the photograph in the recipient chat was recorded. Descriptive statistics, coefficient of variation, Pearson correlation, and an analytical latency budget derived from the firmware structure were used for analysis. All triggers inside the threshold zone produced a successfully delivered photograph and an accompanying distance message, giving a delivery success rate of one hundred percent, whereas the object at 120 cm correctly produced no transmission. End-to-end latency ranged from 6.03 s to 10.45 s with a mean of 8.09 s, a standard deviation of 1.80 s, and a coefficient of variation of 22.3%. The correlation between latency and object distance was weak and statistically insignificant, confirming that latency is dominated by the secure transport layer and the image payload rather than by the sensing stage. Reducing the capture resolution and reusing the secure session are recommended as the most effective optimisation measures.]]>
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