Skype for Business calling plans are an add-on to the Office 365 E5 plan. Although you could theoretically add a-la-carte conference calls and PBX services to the E3 plan, doing so adds $12/month to the cost. This is almost as much as the $15/month difference between E3 and E5, so it's not typically worth it—especially when you factor in other E5 features such as Power BI Pro or Exchange Advanced Threat Protection.
Combined with the $35/month cost of the E5, voice calling will add another $12/month for domestic calling or $24/month for unlimited international calls. So, all-in, you'll be spending $47 or $59/month per line. How does one justify such an expense?
For starters, when you factor out the cost for ...
