Steps for migrating from Cisco Calling to Teams Calling

Start by selecting the target PSTN connectivity model—Direct Routing is usually the migration bridge when Cisco must coexist with Teams—and then pilot users, validate calling and emergency services, port numbers in controlled batches, and retire Cisco only after acceptance.

1. Discovery and requirements

Create a current-state inventory before configuring Teams:

• Cisco users, extensions, direct inward dial numbers, and sites.
• PSTN carriers, SIP trunks, contracts, billing telephone numbers (BTNs), and service addresses.
• Call handlers, hunt groups, contact centers, auto attendants, call queues, voicemail, recording, compliance, and fax.
• Analog equipment: elevators, alarms, paging, door entry, modems, and fax machines.
• Desk phones, conference rooms, survivability requirements, and remote users.
• Emergency-calling obligations for every country and site.
• Dial plan details: extension lengths, normalization, caller ID, toll restrictions, and special numbers.
• Network readiness: Internet circuits, firewalls, DNS, QoS, Wi-Fi, VPN, and branch resiliency.

Use the inventory to produce a feature-mapping matrix: Cisco feature → Teams replacement → migration method → owner → test case.

2. Select the PSTN architecture

Teams Phone supports four principal connectivity choices ^1^:

• Microsoft Calling Plan: Microsoft becomes the carrier.
• Operator Connect: a participating operator manages PSTN connectivity.
• Teams Phone Mobile: selected mobile operators integrate SIM-based calling.
• Direct Routing: your carrier and a supported, customer-provided Session Border Controller (SBC) connect to Teams.

For staged Cisco coexistence, complex routing, existing carrier contracts, or analog integration, assess Direct Routing first. It supports connections to existing PSTN carriers and third-party telephony systems. Its deployment sequence is:

1. Review licensing, infrastructure, and networking.
2. Select a Microsoft-certified SBC.
3. Configure DNS, certificates, firewall rules, and connectivity.
4. Connect the SBC to Teams.
5. Configure voice routes and dial plans.
6. Assign Teams Phone licenses and routing policies.
7. Test inbound and outbound calling before expanding deployment. ^2^

Direct Routing requires users to be homed online, a verified Microsoft 365 domain, an SBC FQDN in that domain, public DNS/IP, a trusted certificate, and the required signaling and media connectivity. It isn't supported in Islands mode. ^2^

A practical coexistence design is:

PSTN carrier
     |
Certified SBC
   /     \
Cisco UC  Teams Phone

Use routing on the SBC/PBX to move users or number ranges incrementally. Confirm the actual Cisco interoperability design and support boundaries with the SBC/Cisco vendors before implementation.

3. Build the Teams foundation

1. Assign each pilot user a Teams Phone license; do not assign the Teams Phone Resource Account license to ordinary users.
2. Voice-enable users.
3. Create tenant dial plans and number-normalization rules.
4. Configure calling, caller-ID, voicemail, and voice-routing policies.
5. Create resource accounts for auto attendants and call queues.
6. Build auto attendants, call queues, holidays, after-hours routing, and shared voicemail.
7. Assign user and service numbers.
8. Configure monitoring and call-quality operations.

The official deployment sequence is licensing, PSTN connectivity, numbers, emergency calling, auto attendants, call queues, other features, and ongoing management ^1^.

4. Configure emergency calling before the pilot

Do not treat emergency calling as a post-cutover task. The implementation sequence is:

1. Assign emergency addresses.
2. Configure network settings.
3. Populate Location Information Service (LIS).
4. Configure emergency policies.
5. Enable users and sites.
6. Test using the locally approved test procedure. ^3^

For Direct Routing, also verify SBC emergency-routing requirements, including PIDF/LO support and any required Emergency Routing Service or ELIN solution. Regulatory and carrier requirements vary by location.

5. Pilot and coexistence

Select pilot users representing headquarters, branches, remote work, reception, executives, delegates, call queues, and accessibility requirements.

Test and record:

• Internal Teams-to-Teams calls.
• Teams-to-Cisco calls in both directions.
• PSTN inbound/outbound and international calls.
• Caller ID, transfers, forwarding, delegation, voicemail, and simultaneous ringing.
• Auto attendants, queues, business hours, and failover.
• Emergency location and security-desk notifications.
• Desk phones, mobile/desktop clients, conference rooms, and analog services.
• Call quality under normal and degraded network conditions.

Keep rollback routing available during each migration wave.

6. Port or retain numbers

The number process depends on the chosen connectivity model:

• Calling Plan: submit the port to Microsoft.
• Operator Connect/Teams Phone Mobile: coordinate with the operator.
• Direct Routing: port or retain numbers through the Direct Routing carrier; the carrier relationship remains with your organization ^4^.

For Calling Plan ports:

1. Request the official customer/account record from the current carrier.
2. Match the business name, account number, BTN, service address, authorized person, and number list exactly.
3. Remove any port freeze.
4. Separate requests where carrier, account/BTN, number type, or service address differs.
5. Allow lead time—typically 7–14 days, potentially up to 30 days—and add time for large orders ^5^.
6. In Teams admin center → Voice → Phone numbers → Numbers → Port, enter numbers manually or upload a one-column PhoneNumber CSV, complete the account information, upload the required authorization documents, and submit ^6^.
7. Track progress under Voice → Phone numbers → Order history.
8. On the confirmed port date, assign numbers and run the acceptance tests.

Do not disconnect Cisco trunks or the losing carrier until every number and service has passed inbound, outbound, emergency, and business-flow testing.

7. Production waves and closure

Migrate by site, department, or number range:

• Freeze Cisco changes before each wave.
• Pre-stage licenses, policies, devices, numbers, and emergency locations.
• Run day-of-cutover tests and publish support contacts.
• Monitor failed calls and quality during hypercare.
• Obtain business-owner acceptance.
• Remove old routing only after stabilization.
• Export required Cisco records, remove unused licenses and trunks, sanitize hardware, and update operational documentation.

For Teams desk phones, separate personal and shared-space designs, secure common-area devices with an admin PIN, use device-lock PINs for personal phones, and deploy updates in validation/general/final phases ^7^.

References

1. Set up Teams Phone in your organization
2. Plan Direct Routing
3. Plan and configure dynamic emergency calling
4. Get phone numbers with Direct Routing uploaded to your tenant
5. What's a port order? - Planning to transfer telephone numbers to Teams
6. Submitting a port request
7. Plan your deployment for Teams Phones