I think your numbers (500k) might be right for September. Based on your guess of 50k customers in April, a 1,000% increase would bring us to 500k customers by the end of September. If we are able to sustain that recent 10x monthly growth rate, we might be closer to 700k today, or more.

Assuming we averaged 18,000 customers per month starting on Jan 1, 2015 to the end of August, 2015, we would have about 144,000 customers, which is almost exactly what NTEK reported at the shareholder meeting on Aug 22nd. A 10x monthly growth rate over the past few months would suggest that we would be averaging 180,000 new customers per month. If we can sustain that growth and add 180,000 new customers per month from Sept till Dec 31st, we'd pick another 540,000 new customers. Add that to the 500,000 at the end of September, and we'd break 1 million by the end of the year. Mind you, there are a TON of assumptions here (e.g., we'd have to assume we can sustain the 10x month-over-month growth rate till the end of the year), so take it for what it's worth—just a guess.