Microsoft Teams Shared Calling — Everything You Need to Know

For years, enabling PSTN calling in Microsoft Teams meant one thing: assign every user their own phone number. For a 5,000-user organization where only 2,000 people actually need to make external calls, that meant paying for 5,000 Calling Plan licenses or 5,000 Direct Routing sessions — even if 60% of those users only needed to receive the occasional transferred call or make one external call per month.

Shared Calling changes this equation fundamentally. Introduced in late 2023 and now generally available, it allows Teams users to make and receive PSTN calls using a shared resource account's phone number — without needing their own personal DID. This is the most significant cost optimization feature Microsoft has added to Teams Phone since its launch.

What is Shared Calling?

In the simplest terms: instead of assigning a phone number to every user, you assign a phone number to a resource account linked to an Auto Attendant. Users are then assigned a Shared Calling policy that points to that resource account. When they make outbound PSTN calls, the caller ID shows the resource account's number (your company's main number). For inbound calls, the Auto Attendant handles routing to the correct person.

The Before and After

Before Shared Calling (Traditional Model):

User A: +1-425-555-0001 (personal DID)

User B: +1-425-555-0002 (personal DID)

User C: +1-425-555-0003 (personal DID)

Each user needs: Teams Phone license + phone number + Calling Plan or DR

With Shared Calling:

Resource Account: +1-425-555-0000 (company main number)

User A, B, C: No personal numbers — use the shared number for outbound

Auto Attendant: Routes inbound calls to users by name/extension

Each user needs: Teams Phone license + Shared Calling policy (no number needed)

Who Should Use Shared Calling?

Shared Calling is ideal for:

Frontline workers who occasionally need to call customers but don't need a personal DID

Back-office staff who rarely make external calls

Retail employees who use a store's main number for outbound calls

Healthcare workers who call patients from a department number

Organizations migrating from PBX where users had extensions, not DIDs

Cost-conscious deployments where assigning 5,000 DIDs isn't justified

Shared Calling is NOT ideal for:

Executives who need a personal direct number

Sales teams where personal caller ID matters

Users who receive high volumes of direct inbound calls

Contact center agents (use Call Queue instead)

Prerequisites and Licensing

Before configuring Shared Calling, ensure you have:

The cost savings are significant. Instead of 5,000 Calling Plan licenses at $8-$12/user/month, you might need only 500 personal numbers plus a few resource accounts with Pay-As-You-Go minutes for Shared Calling users. The savings can be 50-70% on PSTN costs.

Step-by-Step Configuration

Step 1: Create a Resource Account

In Teams Admin Center → Voice → Resource Accounts → Add:

Display name: Main Line - Shared Calling

Username: mainline-shared@contoso.com

Resource account type: Auto Attendant

Or via PowerShell:

New-CsOnlineApplicationInstance -UserPrincipalName mainline-shared@contoso.com -DisplayName "Main Line - Shared Calling" -ApplicationId "ce933385-9390-45d1-9512-c8d228074e07"

Step 2: License the Resource Account

Assign these licenses in Entra ID (Azure AD):

Microsoft Teams Phone Resource Account license

Microsoft Teams Domestic Calling Plan (or Pay-As-You-Go)

For Direct Routing: No calling plan needed — just the Resource Account license.

Step 3: Assign a Phone Number to the Resource Account

In Teams Admin Center → Voice → Phone Numbers → Assign to the resource account.

Or PowerShell:

Set-CsPhoneNumberAssignment -Identity mainline-shared@contoso.com -PhoneNumber "+14255550000" -PhoneNumberType DirectRouting

Step 4: Assign Emergency Address

This step is critical — you cannot create a Shared Calling policy without an emergency address on the resource account.

Set-CsPhoneNumberAssignment -Identity mainline-shared@contoso.com -PhoneNumber "+14255550000" -PhoneNumberType DirectRouting -LocationId

Get the LocationId with:

Get-CsOnlineLisLocation | Select LocationId, Location, City

Step 5: Create an Auto Attendant

In Teams Admin Center → Voice → Auto Attendants → Add:

Name: Main Line Auto Attendant

Resource account: mainline-shared@contoso.com

Time zone and language: Set appropriately

Call flow: Configure greeting, menu options, or dial-by-name

Business hours: Set your operating hours

After hours: Configure voicemail or alternate routing

The Auto Attendant handles all inbound calls to the shared number and routes them to the appropriate user via name dial, extension dial, or menu selection.

Step 6: Create the Shared Calling Policy

In Teams Admin Center → Voice → Shared Calling Policies → Add:

Name: Main Line Shared Calling

Resource account: mainline-shared@contoso.com

Emergency callback numbers: Add numbers from your number pool (must match resource account number type and country)

Or PowerShell:

New-CsTeamsSharedCallingRoutingPolicy -Identity "MainLineShared" -ResourceAccountObjectId -EmergencyNumbers @{add="+14255551111","+14255551112"}

Step 7: Enable Enterprise Voice for Users

Each Shared Calling user must have Enterprise Voice enabled but NO phone number assigned:

Set-CsPhoneNumberAssignment -Identity user@contoso.com -EnterpriseVoiceEnabled $true

Important: Do NOT assign a phone number to Shared Calling users. If a user has both a personal number and a Shared Calling policy, the personal number takes precedence.

Step 8: Assign the Shared Calling Policy to Users

Grant-CsTeamsSharedCallingRoutingPolicy -Identity user@contoso.com -PolicyName "MainLineShared"

Or assign to a group:

New-CsGroupPolicyAssignment -GroupId -PolicyType TeamsSharedCallingRoutingPolicy -PolicyName "MainLineShared"

Step 9: Configure Voice Routing Policy (Direct Routing Only)

For Direct Routing deployments, Shared Calling users need a Voice Routing Policy with PSTN usages that match the resource account's routing:

Grant-CsOnlineVoiceRoutingPolicy -Identity user@contoso.com -PolicyName "SharedCallingVRP"

How Calls Work with Shared Calling

Outbound Calls

User opens Teams dialer and dials an external number

Teams applies the Shared Calling policy → identifies the resource account

The call is placed using the resource account's phone number as caller ID

The called party sees the company's main number (not the user's name or personal DID)

If the called party calls back, the call goes to the Auto Attendant

Inbound Calls

External caller dials the company's main number

The call reaches the Auto Attendant linked to the resource account

The Auto Attendant plays the greeting and offers options:

- Dial by name (caller says or types the person's name)

- Dial by extension (if configured)

- Menu options ("Press 1 for Sales, 2 for Support...")

The call is transferred to the internal user

Emergency Calls

User dials 911 (or local emergency number)

Teams uses the emergency callback number from the Shared Calling policy

Location information (from dynamic E911 configuration) is included

If the PSAP calls back, the call routes to the emergency callback number, not the Auto Attendant

Advanced Scenarios

Multiple Shared Calling Policies

You can create multiple policies for different departments:

Sales Department: Uses +1-425-555-1000 (Sales Auto Attendant)

Support Department: Uses +1-425-555-2000 (Support Auto Attendant)

General Staff: Uses +1-425-555-0000 (Main Auto Attendant)

Each policy points to a different resource account with its own phone number and Auto Attendant.

Hybrid: Some Users Personal, Some Shared

A single tenant can mix personal numbers and Shared Calling:

Executives: Personal DIDs (+1-425-555-0001, etc.)

Sales team: Personal DIDs (for callback purposes)

All other staff: Shared Calling policy

This hybrid model gives you the best of both worlds — personal numbers where they matter, shared calling where they don't.

Multi-Site Shared Calling

For organizations with multiple offices, create separate Shared Calling policies per site:

New York office: +1-212-555-0000 → NY Auto Attendant

London office: +44-20-7946-0000 → London Auto Attendant

Mumbai office: +91-22-2345-0000 → Mumbai Auto Attendant

Each site's users get the local Shared Calling policy, ensuring outbound calls show the correct local number.

Common Mistakes and Troubleshooting

Mistake 1: No Emergency Address on Resource Account

Symptom: "Save" button greyed out when creating Shared Calling policy

Fix: Assign an emergency address to the resource account's phone number before creating the policy

Mistake 2: User Has Both Personal Number and Shared Policy

Symptom: User's outbound calls use personal number, not shared number

Fix: Remove the personal number if you want Shared Calling to take effect. Personal numbers always take precedence.

Mistake 3: No Voice Routing Policy (Direct Routing)

Symptom: Shared Calling users can't make outbound PSTN calls

Fix: Assign a Voice Routing Policy with valid PSTN usages to each Shared Calling user

Mistake 4: Resource Account Not Licensed

Symptom: Phone number can't be assigned to resource account

Fix: Assign both the Teams Phone Resource Account license AND a Calling Plan (or configure DR) to the resource account

Mistake 5: Forgetting Pay-As-You-Go Minutes

Symptom: Outbound calls fail after a period of use

Fix: For Calling Plan resource accounts, ensure Communication Credits or a Pay-As-You-Go plan is funded. When minutes run out, outbound calls stop.

Mistake 6: Emergency Callback Number Mismatch

Symptom: Policy creation fails or emergency calls don't route correctly

Fix: Emergency callback numbers must match the phone number type (DirectRouting, CallingPlan, or OperatorConnect) AND country of the resource account.

Cost Comparison: Shared Calling vs Traditional

For a 2,000-user organization where 500 users need personal DIDs:

The exact savings depend on call volume, but for organizations where most users make fewer than 20 external calls per month, Shared Calling is dramatically more cost-effective.

Limitations to Be Aware Of

Shared Calling users cannot receive direct inbound calls — all inbound goes through the Auto Attendant

Caller ID on outbound calls shows the shared number, not the user's identity

Call Park, Call Pickup, and Delegate features work differently with Shared Calling

Not supported in certain countries (Romania, Czech Republic, Hungary, Singapore, New Zealand, Australia, Japan as of 2025)

Emergency callback requires careful configuration of the number pool

Final Thoughts

Shared Calling is one of the most underutilized features in Teams Phone. Every organization I've assessed has users who don't need personal phone numbers but still need occasional PSTN access. Shared Calling fills this gap elegantly — and the cost savings are real.

My recommendation: audit your organization's call patterns. Identify users who make fewer than 5 external calls per week. Those users are prime candidates for Shared Calling. The ROI speaks for itself.

Need help setting up your resource accounts and voice routing for Shared Calling? SwiftM365 can generate resource accounts in bulk, configure dial plans, and build voice routing policies — all from a simple web interface.

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Have questions about Shared Calling configuration? Reach out via our feedback page or contact me directly at +91 9011070193.