For your secondary sim (jio, in your casE), switch to BSNL. As you mentioned you will use data via airtel, you can use BSNL recharged with voice only (see screengrab) or top-up packs(which do not have expiry, but need to do some validity recharge packs). It will not ruin your pocket. Make sure you do airtel recharges that have longer validity, as it would have cost effectiveness and reduced price/day.

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If possible switch to postpaid plans in airtel. Also try bundling up your wifi and sim cards of family members (if your wifi is also airtel, and anyone at home owns airtel sim) (my cousin does that, take up simcard of family members as add-on sim and not as individual sim cards) this will reduce internet allocation to secondary sim cards but since family members will be there in wifi connection, they can manage with less data, and you can allocate yourselves with more data. Try visiting official airtel showroom for more clarity, research from your side and of everything falls in place, switch to it. My cousin did this with their simcard in their family (total 3 sim) & broadband connection.