Yes, Vivo S1 does have a 3.5mm headphone jack.
Jio offers benefits worth Rs.10,000 on Vivo S1 mobile phone.
Yes, Vivo India does provide a complimentary protective case inside the Vivo S1 standard packaging.
Vivo S1 has 6.38 inches of AMOLED Full HD plus display. It is further protected with Corning Gorilla Glass 5 level of protection. The mobile has a 90% screen-to-body ratio and has 19.5:9 aspect ratio. Vivo S1 offers 404 PPI of resolution.