Do I need to change my landline number while switching to BSNL FTTH?

Recently, I got to know about the wonderful offers provided by BSNL fiber network. However I have heard various speculations that in order to switch to that service, I would need to change my landline number. I have been using this number for more than 15 years and I cant afford to change it. So can I retain my phone number and avail these services?
Well, BSNL has a weird process due to which above confusion has come in. When we opt for new broadband connection, the connection comes with same existing telephone.
But when we opt for new ftth separate telephone number series is allocated, separate bill number etc,along with fibre connection. It's up to the user to activate internet telephony voice calls on new telephone number[it's all free,24x7 to any network].
Old telephone will continue to exist with tariff charged accordingly,like fixed monthly charges,usage charges etc. Ppl will start getting two bills though.
1for old telephone. 1 for new fibre and new telephone(optional activation) under that.
This is something that could be improved by BSNL.