[Home](./index.md) > [sip.js](./sip.js.md) > [SessionState](./sip.js.sessionstate.md) ## SessionState enum [Session](./sip.js.session.md) state. Signature: ```typescript export declare enum SessionState ``` ## Enumeration Members | Member | Value | Description | | --- | --- | --- | | Established | "Established" | If Inviter, sent INVITE and received 200 final response and sent ACK. If Invitation, received INVITE and sent 200 final response. | | Establishing | "Establishing" | If Inviter, sent INVITE and waiting for a final response. If Invitation, received INVITE and attempting to send 200 final response (but has not sent it yet). | | Initial | "Initial" | If Inviter, INVITE not sent yet. If Invitation, received INVITE (but no final response sent yet). | | Terminated | "Terminated" | If Inviter, sent INVITE and received non-200 final response (or sent/received BYE after receiving 200). If Invitation, received INVITE and sent non-200 final response (or sent/received BYE after sending 200). | | Terminating | "Terminating" | If Inviter, sent INVITE, sent CANCEL and now waiting for 487 final response to ACK (or 200 to ACK & BYE). If Invitation, received INVITE, sent 200 final response and now waiting on ACK and upon receipt will attempt BYE (as the protocol specification requires, before sending a BYE we must receive the ACK - so we are waiting). | ## Remarks The [Session](./sip.js.session.md) behaves in a deterministic manner according to the following Finite State Machine (FSM). ```txt ___________________________________________________________ | ____________________________________________ | | | ____________________________ | | Session | | | v v v Constructed -> Initial -> Establishing -> Established -> Terminating -> Terminated | |___________________________^ ^ |_______________________________________________| ```