This article provides steps on how you can Bring Your Own Carrier (BYOC) into Freshcaller.  

Before proceeding, check if your carrier supports the following BYOC technical requirements. 

Note: BYOC can only be configured if your carrier supports the following prerequisites. 

Requirements for inbound BYOC:

1. Check if your carrier supports SIP forwarding of incoming calls to SIP domains in the format number@[customer-name].sip.us1.twilio.com over the Public Internet.
2. Check if your carrier supports G.711/μ-law or G.711/a-law codec for VOIP calls.
3. Send us the list of IP addresses your carrier uses to send calls (SIP invite and media signals) so that we can whitelist them.
4. Make sure your carrier sends the SIP invite in the format we send. You will receive a SIP domain in the format [email protected] for each number that your carrier would need to send the SIP invite and media traffic.

Requirements for outbound BYOC:

1. Check if the carrier can whitelist the list of IP addresses we send for uninterrupted connection and communication.
2. As we do not support username/password authentication for outbound calls, check if the carrier can work without this. 
3. Send the SIP domain or IPs that will be used for forwarding outbound calls generated using Twilio's APIs sent from Twilio SBC.
   We have the capability to forward outbound calls to multiple SIP domains or IPs. If there are two outbound SIP domains or IPs, then once SIP domain 1 (IP 1) is loaded with the maximum number of calls, calls will be forwarded to SIP domain 2 (IP 2).

Once the carrier has confirmed that they support the BYOC prerequisites, then please follow the below steps. 

Configuring BYOC for inbound calls only

1. Send the following details to [email protected]:
   • The list of phone numbers you want to use in Freshcaller.
   • The list of IP addresses that your carrier uses to forward the calls. These IP addresses will be added to our whitelist.

2. Once we receive the numbers, we will generate SIP domains to identify each number.
   For example, if your phone number is "xxx", your SIP address will be sip:user@xxx-sip.twilio.com. The SIP address ensures that the calls are forwarded to Freshcaller. 

3. After you receive the SIP domains, send the domains to your carrier so that they forward the calls to the right domains. 

4. Ensure that your carrier supports G.711/μ-law and G.711/a-law codec for sending calls.

Configuring BYOC for inbound and outbound calls

Note: For inbound calls, make sure to send the details requested in the above section. 

1. Go to Admin Settings > Channels > Phone.
   
2. Click Manage Numbers and choose Caller IDs.
   
3. Click on the Add new caller ID option.
   
4.  Add the phone number with the country code as the caller ID. For example, +1xxxxxxxxxx.
   
5. You will receive a call to verify the phone number. The verification call is mandatory to ensure that the external number belongs to you.
   
6. Once your number is verified, you can use it as your caller ID.
7. Send the details of SIP URI or IP provided by your carrier for each number to [email protected]. Your carrier may provide one or more SIP URIs for a single number. If there are multiple SIP URIs, specify the priority order provided by the carrier with a range of 0 to 65535.

Firewall restrictions - whitelisting IP

The following table gives you the list of IP addresses that we recommend you to whitelist. However, you can choose to whitelist the IPs based on your preferred region to route calls. For example, if you want to route calls from North America Virginia region, you can choose to whitelist only the IPs and ports mentioned for that region and leave the rest.

For more information, refer to — https://www.twilio.com/docs/voice/api/sip-interface#sip-connection-technical-specifications

If you face any issues, reach out to [email protected].

Note: If you are not familiar with whitelisting, contact your carrier for the same