What's a good package/price point for a mid-sized corporate to get for company smartphones?

Currently we pay around $35/month for 100mb data, and free calls to & from all other company phones - landine & mobile. txts are 17c, no freebies, and calls are fairly standard price, again no free minutes. So in effect, the company is our bestmate. Company has approx 100 smartphones, and at least double that of dumbphones. 


100mb feels a bit tight for modern smartphones, although its liveable if you make the effort to connect to wifi wherever possible. And no free txts hits some users more than others, probably not a big deal to the current average smartphoner (male, over 50) but as they spread through the company, the younger folks are noticing the dent in their bill, 5-10 17c txts a day over a month adds up pretty quickly to an extra $30-$50 on the bill for something that costs the provider bugger-all.