Making a call from a Toll-Free number to another Toll-Free number is generally not recommended. This is because the organization responsible for the Toll-Free number, known as the RespOrg, specifies which carrier should handle the call, usually based on geographic codes like LATA or NPANXX.
If only a Toll-Free number is involved, some RespOrgs might not have a set path for the call, causing it to fail with a message like "This destination is not available from your calling area." The same issue can occur with international calls to Toll-Free numbers, often because RespOrgs want to avoid the higher costs associated with routing calls from areas not covered by valid LATA or NPANXX codes.
Here's what we recommend for successful call routing:
- Call from a valid US Automatic Number Identification (ANI):
- This is in line with Flowroute's Outbound ANI Requirements.
- Include a valid P-Charge-Info header in the initial SIP invite:
- Also known as a Billing Telephone Number (BTN), this header provides the BTN if it differs from the 'From' number.
- Utilize the P-Asserted-Identity (PAI) header in the initial SIP invite.
- This is a less reliable option compared to P-Charge-Info, as some carriers may remove the PAI header before routing the call.
Using Toll-Free numbers as the 'From' number for outgoing calls presents a unique set of challenges, primarily because the receiving end may block such calls. This is often due to the complexities of billing and routing associated with Toll-Free numbers.
To successfully complete the call, when dialing other Toll-Free numbers, it's crucial to include a valid billing telephone number in the 'p-charge-info' header of the initial SIP (Session Initiation Protocol) invite. This header serves as a mechanism for the terminating carrier to identify the billing details, therefore providing a more defined routing process.
Billing for calls made from Toll-Free numbers is particularly complicated. The rate charged to the terminating end is determined based on the 'From' number. Calls that originate from numbers without a defined location, such as other Toll-Free numbers, will likely result in a failed call. This is because Flowroute, which manages the Toll-Free number, may not have a billing identity and will not be able to create a billable receipt for the call.
To mitigate the challenges associated with missing billing rates and routing complexities, some Toll-Free numbers are configured to disallow incoming calls from numbers without a defined location. When this happens, callers may encounter an error.
When getting this error, Flowroute's system will not provide a voice error via operator recording. The call will drop the line. This is a protective measure taken by the RespOrg or the terminating carrier to avoid incurring higher costs and to simplify the routing process.
Therefore, including a valid billing telephone number in the 'p-charge-info' header is not just a best practice but often a requirement for successful call completion. It allows the terminating carrier to accurately bill the end user and facilitates more reliable and cost-effective routing. By adhering to this practice, users can significantly improve the success rate of calls made from Toll-Free numbers, ensuring more effective and efficient communication.