What a month of finding out late costs a small ISP

A 3,000-home ISP that hears about outages from customers loses about Rs 75,000 a month. Each number is a slider you set, a sourced figure, or a stated assumption. Replace any of them with your own.

The method in one line

The cost instrument on our home page states it this way.

This page shows every step behind that sentence.

The instrument does one more thing with the 24% figure. It scales that share with your fault exposure. Exposure is network faults times homes behind a fault, divided by homes. At the defaults that is 6 times 30 over 3,000, or 6%. At 6% exposure the share is exactly the survey’s 24%. An ISP with twice the exposure loses twice as many homes to uptime. The share is capped at 60%. That scaling is a stated assumption. No survey measures it.

What finding out late means

A branch fault is a PON, an uplink, a pole box or a cut. About 30 homes sit behind one. The model assumes six of these a month.

Without monitoring, the first sign is the phone. Allow 30 minutes until the first customer calls. Allow 30 more while the group argues and someone is sent. That is 60 minutes before the crew moves.

With the box in the rack, confirmation takes about ninety seconds. Dispatch takes ten minutes more, because the PON is already named. Call it 12 minutes. Repair starts 48 minutes earlier on every branch fault.

Those 48 minutes are why fewer homes leave over uptime. We do not price those 48 minutes as crew wages. Counting them twice would inflate the answer.

The inputs

Notes on the figures that are not yours

Plan price, Rs 500. Jio AirFiber starts at Rs 599 a month. Airtel Xstream AirFiber starts at Rs 699. Smartprix listed both tables, read 17 September 2026. Rs 500 is already the floor. Put your own average realisation here.

Churn, 3% a month. Indian ISP churn is reported at 3 to 5% a month. We take the low end. A large operator’s founder put cable churn at 3% in a 2024 interview. Both are reported figures, so treat them as a range. A 3% monthly churn gives a customer life of 33 months.

Leavers who go over uptime, 24%. LocalCircles surveyed over 140,000 people across 333 districts in April 2025. Two thirds said they would switch provider. Uptime and service quality was the top reason, at 24%. Speed came next at 22%, and price at 18%. This one is a primary source.

Share the box keeps, 1 in 3. No survey gives this number. We set it low on purpose. Two in three homes that were going to leave still leave.

Contribution, Rs 225 a home a month. That is 45% of Rs 500. Bandwidth, power and field cost take the rest. Use your own gross margin if you track it.

Replacement cost, Rs 2,500. An ONU costs about Rs 1,000. Syrotech and Netlink units trade between Rs 850 and Rs 1,250 on IndiaMART. Drop cable and connectors add Rs 400. Labour adds Rs 600. Sales commission adds Rs 500.

Technician cost, Rs 125 an hour. That is Rs 25,000 a month over 200 working hours. Indeed India puts the average network technician at Rs 24,678 a month.

Individual faults, 90 a month. TRAI’s quality rules work to three faults per 100 homes a month. Three per hundred on 3,000 homes is 90. These are single-home faults, counted apart from the six branch faults.

The arithmetic, step by step

Step 1. Who leaves this month

3,000 homes at 3% churn is 90 homes a month. That is the whole leaving crowd, for every reason.

Step 2. Who leaves over uptime

24% of 90 is 21.6 homes. These are the homes that go because repair was slow.

Step 3. Who the box keeps

One in three of 21.6 is 7.2 homes. Call it about seven homes a month. We carry the unrounded 7.2 into the money below.

Step 4. What a kept home is worth

A home contributes Rs 225 a month and stays 33 months. Rs 225 times 33 is Rs 7,425 of lifetime contribution.

Step 5. What replacing a lost home costs

Every home you lose must be replaced to hold your subscriber count. That costs Rs 2,500 in hardware, labour and commission.

So one saved home is worth Rs 7,425 plus Rs 2,500, or Rs 9,925. Multiply by 7.2 homes. The churn line is Rs 71,460 a month.

Step 6. Crew hours on “where is it”

Ninety individual faults a month, at 40 minutes of diagnosis each. A map of the plant halves that to 20 minutes. Ninety faults times 20 minutes is 1,800 minutes, or 30 hours. At Rs 125 an hour the crew line is Rs 3,750 a month.

Step 7. Rebates under the 2024 rules

A fault that runs past three working days owes the customer a validity extension. Six branch faults touch 30 homes each, so 180 homes a month. Rs 500 over 30 days is about Rs 16.67 a day. We assume 8% of those homes drift past the deadline. 180 times Rs 16.67 times 8% is Rs 240 a month.

The rupees are small here. The TRAI 2024 quality rules matter more once you file quarterly.

What the month costs

Round that to about Rs 75,000 a month, or about Rs 9 lakh a year. The ISP bills Rs 15 lakh a month, so the loss is 5% of revenue. Churn is 95% of the total. The crew hours and the rebates barely move it.

The same arithmetic at 10,000 homes

Hold every rate and hold fault exposure at 6%. Three hundred homes leave a month. Seventy-two of them leave over uptime. The box keeps 24, at Rs 9,925 each, or Rs 2,38,200. Three hundred individual faults give 100 crew hours, or Rs 12,500. We leave the rebate line at Rs 240, because it is too small to matter.

That is about Rs 2.5 lakh a month, or about Rs 30 lakh a year.

At that size the ISP also files quarterly with TRAI. A missed benchmark costs Rs 1 lakh the first time. From the third time it is Rs 3 lakh. Those penalties sit outside this model.

The weak points

• The 1 in 3 keep rate has no survey behind it.
• Rs 225 of contribution is a guess at your cost base.
• Six branch faults a month may be high or low for you.
• The 40-minute diagnosis assumes nobody has a map of the plant.
• The 24% share is surveyed, but scaling it by exposure is ours.

So divide every assumption by three and run it again. The loss falls to about Rs 25,000 a month. That is still about twice the software bill.

Replace anything you know better

Six numbers are yours, and you already have most of them.

• Homes. Count the ones lit today, from your OLT roster.
• Plan price. Your average realisation a home, after discounts.
• Network faults a month. Count last month’s from your own group chat.
• Homes behind a fault. Your typical PON or pole box size.
• Churn. Your own leavers divided by your own base.
• Contribution. Your gross margin after bandwidth, power and field cost.

Swap those six and the rest of the model still stands. The two survey figures, 24% and 3%, stay. Change those only if you hold better Indian data.

What the fix costs the same network

HansaNet is Rs 3 a home a month. Three thousand homes is Rs 9,000, or Rs 10,620 with 18% GST. Against Rs 75,450 that is about seven to one. Rs 2,000 opens the account as credit against your own bills, and nothing is installed on your OLT. See the pricing page and how outages are detected.

Sources

All read 17 September 2026.

• localcircles.com/a/press/page/india-broadband-service-survey. LocalCircles broadband survey, April 2025, over 140,000 respondents in 333 districts. Primary.
• brightcrm.in/isp-industry-statistics. ISP industry statistics page, monthly churn of 3 to 5%, no underlying study named. Reported.
• business-standard.com, April 2024 interview. A broadband chief executive puts cable churn at 3%. Reported.
• smartprix.com, AirFiber plan comparison, 2026. Entry plan prices of Rs 599 and Rs 699. Reported.
• in.indeed.com/career/network-technician/salaries. Average network technician salary in India, Rs 24,678 a month. Reported.
• indiamart.com, EPON and GPON ONU listing. Street prices of Rs 850 to Rs 1,250 a unit. Reported.