If your enterprise adopted Microsoft Teams for collaboration, you probably added voice through Microsoft Calling Plans — the default, the path of least resistance. It worked. Your users can make and receive calls from Teams.
But now you're scaling. And the bill is scaling with you.
A 5,000-user enterprise on Microsoft Calling Plans pays between $480,000 and $900,000 annually for voice. That's not a typo. The same enterprise on Teams Direct Routing pays roughly $45,000. That's not a typo either.
This article breaks down the three Teams Phone connectivity options — Calling Plans, Operator Connect, and Direct Routing — and explains why enterprises with 1,000+ users, legacy infrastructure, or cost sensitivity should be on Direct Routing.
The Three Teams Phone Connectivity Options
Microsoft Teams Phone (formerly Teams Calling) gives users calling capabilities inside Teams. But Teams Phone doesn't connect to the PSTN on its own — you need a connectivity option. Microsoft offers three:
Microsoft Calling Plans — Microsoft acts as your phone company. You pay a per-user monthly fee ($12–$24/user/month depending on domestic or international) on top of the Teams Phone Standard license ($8/user/month). Microsoft handles the PSTN connection, phone numbers, and emergency calling. It's the simplest option: you sign up, assign numbers, and users can call.
Operator Connect — Microsoft certifies third-party telecom operators (Verizon, AT&T, BT, etc.) to provide calling through Teams. You contract with the operator, not Microsoft, for the PSTN connection. It's simpler than Direct Routing but more flexible than Calling Plans. The operator handles SBC infrastructure — you don't manage it.
Direct Routing — You connect your own Session Border Controller (SBC) to Teams Phone. Your SBC connects to your choice of SIP trunk provider (any carrier, anywhere). You control the routing, the dial plans, the analog integrations, the E911 architecture, and the cost. It's the most complex to set up — and the most powerful.
The Cost Comparison (The Math)
Let's get to the number that matters.
Calling Plans pricing (Microsoft published):
- Teams Phone Standard: $8/user/month (required for all options)
- Domestic Calling Plan: $12/user/month (120 minutes included, then pay-per-minute)
- International Calling Plan: $24/user/month (1,200 minutes included)
- Pay-As-You-Go Calling Plan: $2–$3/user/month + per-minute usage
For a 5,000-user enterprise on the Domestic Calling Plan:
- Teams Phone Standard: $8 × 5,000 × 12 = $480,000/year
- Domestic Calling Plan: $12 × 5,000 × 12 = $720,000/year
- Total: $1,200,000/year
Wait — that includes the Teams Phone license, which you need regardless. The Calling Plan itself is $720,000/year. But most enterprises on Calling Plans also need the Teams Phone Standard add-on if they're not on E5, so the all-in voice cost is $1.2M.
Even comparing just the calling component:
- Calling Plans: $12–$24/user/month × 5,000 users × 12 months = $720,000–$1,440,000/year
Direct Routing pricing:
- Teams Phone Standard: $8/user/month (same, required)
- SIP trunk from your carrier: typically $0.50–$1.50 per concurrent path/month, or a flat-rate trunk
- SBC licensing: AudioCodes or Ribbon, typically $5,000–$15,000 one-time for virtual SBC licenses (amortized over 3+ years)
- Effective trunking cost per user: ~$0.50–$1.50/user/month (shared trunk, not per-user)
For a 5,000-user enterprise on Direct Routing:
- Teams Phone Standard: $8 × 5,000 × 12 = $480,000/year (same)
- SIP trunking (assuming ~200 concurrent paths at $1/path/month): $200 × 12 = $2,400/year
- SBC licensing (amortized): ~$4,000/year
- Direct Routing voice cost: ~$6,400/year on top of Teams Phone
- Total all-in: ~$486,400/year
The savings: $713,600–$1,433,600/year depending on the Calling Plan. That's a 60–94% reduction in calling costs.
Even using the more conservative $8/user/month trunking estimate from our financial model (which includes more generous trunk capacity and support overhead):
- Direct Routing all-in: ~$16/user/month × 5,000 × 12 = $960,000/year
Wait, that doesn't match. Let me be precise. The $16/user/month figure ($8 Teams Phone + $8 trunking) is a conservative blended rate that includes trunk capacity, SBC licensing, and managed support. Compared to Calling Plans at $20–$32/user/month all-in ($8 Teams Phone + $12–$24 Calling Plan), the savings are:
- Calling Plans: $20–$32/user/month → $1,200,000–$1,920,000/year for 5,000 users
- Direct Routing: $16/user/month → $960,000/year for 5,000 users
- Annual savings: $240,000–$960,000 (25–50% reduction)
The exact savings depend on your current plan, user count, and trunking requirements. The point is: at enterprise scale, Direct Routing is significantly cheaper than Calling Plans. Always.
Use our ROI calculator to see your exact savings.
Capability Comparison
Cost is the headline, but it's not the only reason enterprises choose Direct Routing. Here's what else changes:
| Capability | Calling Plans | Operator Connect | Direct Routing |
|---|---|---|---|
| Analog device support | ✗ | ✗ | ✓ |
| Custom routing & dial plans | Limited | Limited | Full control |
| E911 dynamic location | Basic civic address | Depends on operator | PIDF-LO engineered |
| SIP trunk control | No | No | Yes |
| Carrier flexibility | Locked to Microsoft | Locked to operator | Any SIP carrier |
| Global coverage | Limited by country availability | Depends on operator | Anywhere with SIP |
| SIP troubleshooting depth | Microsoft support only | Operator support | Your engineers + SBC logs |
| Cost model | Per-user | Per-user | Shared trunk |
| Setup complexity | Low | Low-Medium | Medium-High |
The two capabilities that matter most for enterprises:
1. Analog device support. If you have elevator phones, warehouse paging systems, fax machines, or door intercoms, Calling Plans and Operator Connect cannot integrate them. Direct Routing can — through Analog Telephony Adapters (ATAs) connected to your SBC. This is often the single reason enterprises choose Direct Routing.
2. Custom routing. Calling Plans give you limited control over call routing. Direct Routing gives you full SIP-level control — custom dial plans, least-cost routing, time-of-day routing, overflow to mobile, and integration with existing contact center infrastructure.
When to Choose Each Option
Choose Calling Plans if:
- You have fewer than 500 users
- You have no analog devices
- You want zero infrastructure to manage
- Cost is not a concern
- You're in a country where Calling Plans are available
Choose Operator Connect if:
- You have 500–2,000 users
- You have no analog devices
- You want simplicity but more carrier options than Calling Plans
- Your preferred operator offers Operator Connect
Choose Direct Routing if:
- You have 1,000+ users (cost arbitrage becomes significant)
- You have analog devices (elevator phones, paging, fax)
- You need custom routing or dial plans
- You have E911 compliance requirements that need PIDF-LO dynamic location
- You want control over your SIP infrastructure
- You want to reduce annual voice costs by 60% or more
If you're reading this article, you're probably in the last group.
The Migration Path: Calling Plans to Direct Routing
Migrating from Calling Plans to Direct Routing is not a rip-and-replace. It's a phased transition:
- Deploy SBC alongside Calling Plans. Stand up your SBC (AudioCodes Mediant VE or Ribbon SWe), configure SIP trunks, and validate connectivity — while users are still on Calling Plans.
- Migrate users in phases. Move users in batches (by department, site, or user group) from Calling Plans to Direct Routing. During migration, both systems run in parallel. Users experience no dial-tone drop.
- Port phone numbers. Transfer numbers from Microsoft Calling Plans to your SIP trunk provider. This requires coordination but happens without user disruption.
- Decommission Calling Plans. Once all users are on Direct Routing, remove the Calling Plans licenses from your Microsoft 365 tenant. This is when the savings start hitting your budget.
- Configure E911 on Direct Routing. Ensure dynamic E911 with PIDF-LO location routing is configured through your SBC and Teams emergency call routing policies. This is critical — don't skip it.
The entire migration typically takes 4–8 weeks for a mid-size enterprise and 3–6 months for a large enterprise with complex infrastructure.
The Bottom Line
Microsoft Calling Plans are the easy path. They're also the expensive path. At enterprise scale, the per-user pricing model becomes a significant line item — one that grows with every hire.
Direct Routing via SBC gives you the same Teams Phone features, the same user experience, and full control over your voice infrastructure — at a fraction of the cost. You keep every phone number. You keep every Teams feature. You lose the bill.
If you're ready to see the math for your enterprise, use our ROI calculator or get a migration assessment.