Best Business Plan + Phone Combo

G'day All,

Have started a new business and looking to see what is the best Plan + phone combo?

Using me as an example - I am currently spending $30 per month on private/business phone calls through Optus. I'm just interested in hearing your thoughts on what would be a cost effective option for me to take?

Should I buy a phone through one of the many deals posted on here and do a BYO plan? OR do a phone and plan combo (which looks like the clear winner for me)
This will viewed as a company phone (my company)

My use is as follows:
2 - 4 gig per month
6-10 mobile calls max per weekday (half that on weekends)
3 calls to landlines per weekday (half that on weekends)
No international calls

Interested in iPhone 6, Nexus 6p, Nexus 5x, Moto Plus G4, LG G5 - would love to hear your thoughts and recommendations!