As the title says, I am looking for advice for a SIM for my iPhone 6+ for use during a 3 week stay in Dec/Jan. We plan to be in Delhi (4 days), Bangalore (4 days), Haridwar (1 week - but have home wifi access) and traveling in Uttarakhand - roughly in this sequence. Not expecting heavy usage. Would deeply appreciate any advice you might have.

Thank you very much!