Ask your network administrator for your company's ASN. If you are using a public ASN, you must own it. If you don't own one, Twilio will issue a private ASN to you in the 65000 range. This will be used to configure dynamic routing using BGP (Border Gateway Protocol), between Twilio and your network.
To estimate bandwidth, convert your maximum number of concurrent calls to required throughput in Mbps. Many of our customers found the following ratio helpful: 1 Mbps of bandwidth is roughly equal to 10 concurrent G.711 codec calls.
Share IP routes for your border devices with your Twilio on-boarding contact. You'll also need to allow traffic from all Twilio IP addresses through your SBC/Firewalls.
Any router or firewall supporting IPSec VPN should be able to establish a standards based IPSec tunnel to Twilio. You'll receive Twilio's IPSec VPN specification for IPSec Phase I and Phase II. In addition, you'll be able to reference your pre-shared key in Twilio Console.
You can directly make changes to the connection name and account permissions in Console. If you need to modify your bandwidth and IP routes or decommission a connection, please submit a request through Console. For all other changes, please contact support for additional assistance.