Will I retain my SIM & number if I go abroad for 3 months?

Later in the year I’m travelling to India for three months and I’m wondering whether my phone number will be deactivated in that time. I’m aware it will cost me more while roaming but I just want to make sure I won’t lose my phone number for those three months. 

The responses on these forums and the official ID information is unclear. The official line is:

“if you roam more than you use your phone at home (we mean in the UK) over a 4-month period, we might think you’re permanently roaming”

Does that mean that if I use it abroad for two months and a day I’ll be classed as permanently roaming? (as then I’d have used it for abroad for longer than I have in the UK over four months).

Or does it mean that if I use it abroad for four months and a day I’ll be classed as permanently roaming? (if so then the wording could be much clearer).

Apparently if you stay abroad for longer than this unclear period of time then the following happens:

“First of all, we'll send you a text reminding you of the fair usage policy. If you don't change your usage behaviour to comply with it, we'll also ask you to provide some sort of proof that you have strong ties to the UK, like a UK bill or bank statement.

If you don’t provide any proof of having strong ties to the UK, and you continue to roam in the EU more than you use your plan in the UK, we'll apply a surcharge to your EU roaming usage. When we do this we'll send you another text message - to make you're aware of the situation, and give you a second chance to stop roaming and avoid charges”

But this only applies to EU roaming. What about India or any other non-EU country? I don’t plan on using any calls, texts, or data while in India so I’m not bothered if there is a surcharge on top of the standard roaming charges. I’m just worried that they may delete my account and that I’ll lose my number. I’ve heard that this happens with other phone providers but the information provided for ID is either badly worded for EU roaming or non-existent for non-EU roaming. I have heard that with other providers you have to at least send a text each month to show it is still being used - which is something I don’t mind doing in India as texts only cost £0.60.

Sorry for the long question. To summarise: if I go to India for 3 months will I still retain my ID account and my phone number when I return to the UK? 

Thank you!