When a call travels using the IP address 44.238.177.138, even though the IP address is defined as UDP, it switches to TCP and the call doesn't drop. The question is, why does it switch between protocols?

Vapi's SIP signaling IP (44.238.177.138) supports both UDP (port 5060) and TLS (TCP, port 5061). If a call switches from UDP to TCP/TLS, it's typically because UDP is blocked by a firewall or the system requires encrypted signaling. This protocol flexibility ensures calls remain connected even if the preferred protocol is unavailable. Example:

SIP signaling can use:
- UDP: 44.238.177.138:5060
- TLS: 44.238.177.138:5061

For reliable operation, ensure both protocols are allowed in your firewall settings ([documentation](https://docs.vapi.ai/advanced/sip/sip-networking)). Source: - [SIP networking and firewall configuration](https://docs.vapi.ai/advanced/sip/sip-networking)