Migrating from Traditional Phone Systems to VoIP Telephone Systems
Businesses transitioning from traditional phone systems to VoIP telephone systems must ensure a seamless porting process for their existing numbers.
VoIP numbers, like ISDN lines, are assigned in blocks of 10.
Before making the move, it helps to review the key questions to ask when exploring a VoIP telephone system.
Why Businesses Must Port Their Entire ISDN Block
- All telcos in Singapore assign ISDN numbers in blocks of 10 (e.g., XXXX 7800 – XXXX 7809).
- Singapore telecom regulations require businesses to port the entire block when migrating to VoIP telephone systems.
- Even if only one or two numbers are required, port the entire block, then manage any unused numbers via VoIP call routing.
Example: Migrating to a VoIP Telephone System
A company using YYYY 5678 and an ISDN block XXXX 7800 – XXXX 7809 decides to transition to a VoIP telephone system. The migration process includes:
- Porting all ISDN numbers together to the new VoIP provider.
- Deploying VoIP-compatible devices like Fanvil X4U or X6U phones, which connect directly to the cloud.
- Routing calls through the VoIP system, eliminating the need for on-premise PBX hardware.
By choosing to move to cloud-based VoIP phone systems in Singapore, companies modernise their communication setup, gain operational flexibility, and reduce costs.
How Number Porting Works in VoIP Telephone Systems
Number porting requires collaboration between two key parties:
- Losing Carrier: The current telecom provider that holds the numbers.
- Winning Carrier: The VoIP provider receiving the ported numbers.
Businesses must complete a Number Portability Form (NPF) provided by the Winning Carrier.
Signing the form allows the number transfer and must be submitted to the Winning Carrier.
The Winning Carrier then forwards the request to the Losing Carrier and awaits confirmation of a Ready for Service (RFS) date.
Important: Number porting is a coordinated process involving all FBOs (Facilities-Based Operators). Porting occurs at either 12 AM or 3 PM, and customers cannot select a specific time.
Telcos adhere to IMDA’s full number portability guidelines without concessions, making it essential to plan and inform stakeholders.
What Happens on Number Porting Day?
Based on industry experience:
- If porting begins at 12 AM, completion usually occurs by 9 AM, as some telcos do not process requests before 9 AM.
- If porting begins at 3 PM, completion occurs by 4 PM, as some telcos do not complete requests before 4 PM.
Since number porting is a multi-provider operation, occasional clerical errors between FBOs may delay the process.
What to Do If Porting Takes Longer Than Expected?
To assist the Winning Carrier in troubleshooting delays, businesses should conduct a simple call test and provide feedback.
Using a mobile phone, dial the ported landline and document:
- Whether the call is successful.
- The mobile number’s telco.
- The time of the call.
- The mobile number used for testing.
- The landline number being tested.
This information helps the Winning Carrier identify and resolve connectivity issues more efficiently.
Types of Number Porting: FBO vs. SBO
| Porting Between FBOs (Facilities-Based Operators) | Porting from SBO to FBO/SBO |
| For number porting between major FBOs like SingTel, StarHub, M1, or MyRepublic, businesses keep full authority over their numbers. The process is straightforward, provided the business’s details match those recorded with the Losing Carrier. | SBOs (Service-Based Operators) differ from FBOs and are usually smaller VoIP providers. When porting from an SBO to an FBO or another SBO, businesses should note: The SBO, not the business owner, must allow the number porting request. The SBO holds the number rights, meaning their approval is required for any port-out request. Businesses should verify in advance if they can port their numbers to avoid last-minute delays. Disclaimer: If porting from an SBO, the Number Portability Form must be signed by the SBO’s authorised officer. Failure to get their approval will prevent the port from proceeding. OIT’s mainline number is operated by an SBO – Microsoft Teams Phone. |
Required Information for Number Porting
Number Portability Forms may have minor variations across telcos, but all require the following details:
- Business Name / Current Billing Company Name: As listed on the existing telecom bill.
- Unique Entity Number (UEN): The company’s identifier in telco records.
- Service Installation Address: The exact address recorded with the Losing Carrier (even if the business has moved).
- Correspondence Address: If different from the service installation address, provide the mailing address on record.
- Authorised Officer’s Name (as per NRIC/Passport/FIN): Must match the Losing Carrier’s records.
- Authorised Officer’s Designation & Contact Details: Ensure phone number and email accuracy.
Managing Your Numbers During the Porting Process
- ISDN/SIP Users: Contact the Losing Carrier for a full list of associated numbers, including any retention numbers not visible on bills.
- Analog Line Users: Convert or cancel hunting lines before submitting the porting request.
- A recommended approach is forwarding calls to the new provider while number porting is still ongoing.
- SBO Users: Request the full list of numbers assigned to your VoIP subscription.
Post-Porting Considerations
- Once porting is complete, the Losing Carrier will no longer bill for the numbers.
- Do not cancel or re-contract numbers before the porting process is complete. If cancelled, the Losing Carrier will no longer recognise your records, resulting in failed porting.
- Standard porting for ISDN/SIP numbers takes 30 working days. Faster processing may be available at an extra cost.
- Be prepared for retention offers from your Losing Carrier, as they may attempt to persuade you to keep services.
By ensuring accuracy in the porting request and communicating with stakeholders, businesses can transition smoothly from ISDN to VoIP telephone systems without disrupting operations.
