What Happens When You Press Send

You are in Mumbai. It is Tuesday morning. You type a message to a colleague in Singapore, hit send, and watch the single grey tick turn to two grey ticks, then two blue ones.

It took 170 milliseconds.

In that time, your message travelled approximately 6,400 kilometres, passed through four countries’ worth of infrastructure, crossed the floor of the Bay of Bengal, and arrived at a data centre in Jurong West before your thumb had fully lifted off the screen.

None of that journey is invisible. It is physical. It has coordinates.

Here is what actually happened.

Step 1 — The first ten metres

0–3ms

Your phone sends a radio signal to a cell tower within 500 metres of where you’re sitting. This is the noisiest, least reliable part of the entire journey. The submarine cable on the floor of the Bay of Bengal is more stable than the air between your phone and that tower. The packet — your message, sliced into chunks with routing headers — leaves the tower and enters Jio’s core network.

Step 2 — Backhaul: the invisible highway

3–15ms

From the tower, the packet moves through backhaul — the fibre or microwave links connecting cell towers to the core network. In Mumbai, Jio runs almost entirely on buried fibre. Across much of Southeast Asia, microwave links still handle this leg: faster to deploy, cheaper, and adding 5–10ms per relay hop. Your packet is now inside the carrier network, heading for a point of presence where the domestic journey ends.

Step 3 — Under the ocean

15–80ms

This is the part nobody thinks about. Your packet travels along one of several submarine cable systems crossing the Indian Ocean — SEA-ME-WE 5 is the main artery, landing at Versova on Mumbai’s northwest coast before running northeast across the Bay of Bengal to Changi in Singapore. According to TeleGeography, over 400 active submarine cable systems carry more than 95% of international internet traffic. Light moves through the glass fibre at around 200,000 km/s — two-thirds its speed in vacuum. The 4,800km to Singapore takes roughly 24ms of pure propagation. Processing, encryption, and queuing at each end brings the real number to 40–65ms.

Step 4 — Into the data centre

80–100ms

The packet surfaces at Changi and routes to Meta’s data centre in Jurong West — one of a handful of markets globally where Meta operates owned infrastructure rather than rented colocation. WhatsApp decrypts the message, checks your colleague’s account status, verifies the encryption keys. If their phone is reachable, delivery begins immediately. If not, the message waits here — which is why the first tick stays grey.

Step 5 — The return signal

100–170ms

The two-tick confirmation makes the same journey in reverse. The round trip — send, process, deliver, acknowledge — completes in 170 milliseconds. Roughly the gap between two frames of a 12fps video.

Why this looks different from Manila. Or Dhaka. Or the Maldives.

The Mumbai–Singapore route is one of the best-served corridors in Asia. Multiple redundant cable systems. Modern backhaul on both ends. Data centre infrastructure in both cities.

Not all APAC routes are like this.

Manila to Singapore, a shorter distance on the map, has historically suffered from higher latency and more frequent outages because the Philippines sits at the end of a cable topology that was not designed with Manila at the centre. According to GSMA’s State of Mobile Internet Connectivity Report, significant portions of Southeast Asia’s population experience latency above 100ms even for regional connections — before the message has even crossed an ocean.

Bangladesh, Sri Lanka, Myanmar — all markets where the cable infrastructure is thinner, the landing stations fewer, and the backhaul networks less redundant. A message sent from Dhaka to Singapore can take 250ms or more, not because the distance is greater but because the packet has to travel a more circuitous route through fewer, more congested handoff points.

What you are actually sending

Here is the thing about pressing send.

You are not sending a message through the cloud. You are sending a pulse of light along a glass thread on the floor of the Bay of Bengal. You are using infrastructure that took decades and billions of dollars to build, that requires ships to maintain, that nations have strategic interests in controlling.

The cable route from Mumbai to Singapore carries not just WhatsApp messages but banking transfers, equity trades, government communications, medical records, streaming video. It carries, in a meaningful sense, the economic relationship between two of Asia’s most important markets.

And it is not infinite in capacity. When a major cable is cut — by a ship anchor, by an undersea landslide, by deliberate interference — the traffic that was riding it has to reroute, suddenly and at scale, through whatever alternatives exist. In 2022, cable cuts in the Red Sea affected connectivity across South and Southeast Asia for weeks. The backup routes existed, but they were slower, more congested, and more expensive.

The 170 milliseconds feels effortless because a lot of people built a lot of things to make it feel that way.