M Microsoft said it has 320 million paid Office seats as of January 2024 — which is a staggering number. However, considering that Teams leverages the Office bundling strategy, that’s not surprising.vi s Looking at voice calling (VoIP) usage within Teams, there are an estimated 80 million users. Again, that figure overstates its usage for calls that eventually traverse the PSTN. The number of Microsoft phone seats using PSTN for voice is 20 million, Microsoft announced on its earnings call in April 2024. (To use PSTN calling, users need to have a Microsoft Phone System license and a Calling Plan subscription. Alternatively, they can use their own telephony provider with Direct Routing.) Key takeaway: 20 million PSTN-enabled Teams users represent a very small fraction of the total 320 million active Teams user base. M According to communications market research firm Cavell Group, the global business calling market has over 467 million users.viii That figure includes the use of a fixed or mobile telephony line for either internal or external business communications. In the enterprise telephony market, Cavell counts more than 84 million unified communications users, which equates to 18% overall market penetration for Teamss M M In other words, not everybody is using Teams for UC, and there is a significant transition away from existing calling systems that lies ahead. Copyright © 2025 AVANT Communications, Inc. 9