Abstract: Methods and computer program products for establishing communication events between an initiator user and a recipient user over a first communication system. The initiator and recipient users are contacts within a second communication system but are not contacts within the first communication system. For the initiator and recipient users, an association between a first user identity in the first communication system and a second user identity in the second communication system is determined. The initiator user device uses the association for the recipient user to determine the first user identity of the recipient user. A setup request to establish the communication event is sent over the first communication system from a first initiator client to a first recipient client. A communication event is authorized to proceed over the first communication system on the basis that the initiator user and the recipient user are contacts within the second communication system.

Abstract: Methods and computer program products for establishing communication events between an initiator user and a recipient user over a first communication system. The initiator and recipient users are contacts within a second communication system but are not contacts within the first communication system. For the initiator and recipient users, an association between a first user identity in the first communication system and a second user identity in the second communication system is determined. The initiator user device uses the association for the recipient user to determine the first user identity of the recipient user. A setup request to establish the communication event is sent over the first communication system from a first initiator client to a first recipient client. A communication event is authorized to proceed over the first communication system on the basis that the initiator user and the recipient user are contacts within the second communication system.

Abstract: A voice or video call is to be established between a caller and a callee based on a call flow that involves a call establishment request and a corresponding call acceptance response. A first call establishment request is sent to a called terminal (of the callee) that is unready to accept the call upon receiving this first call establishment request. Once the called terminal is ready to accept the call, instead of the call acceptance response, a reverse call establishment request for the call is received back from the called terminal. The reverse call establishment request is automatically accepted on behalf of the caller on condition that the reverse call establishment request was received back from the called terminal within a certain time limit. If so, the call is accepted by sending an instance of the call acceptance response to called terminal.

Abstract: A voice or video call is to be established between a caller and a callee based on a call flow that involves a call establishment request and a corresponding call acceptance response. A first call establishment request is sent to a called terminal (of the callee) that is unready to accept the call upon receiving this first call establishment request. Once the called terminal is ready to accept the call, instead of the call acceptance response, a reverse call establishment request for the call is received back from the called terminal. The reverse call establishment request is automatically accepted on behalf of the caller on condition that the reverse call establishment request was received back from the called terminal within a certain time limit. If so, the call is accepted by sending an instance of the call acceptance response to called terminal.

Abstract: Methods and computer program products for establishing communication events between an initiator user and a recipient user over a first communication system. The initiator and recipient users are contacts within a second communication system but are not contacts within the first communication system. For the initiator and recipient users, an association between a first user identity in the first communication system and a second user identity in the second communication system is determined. The initiator user device uses the association for the recipient user to determine the first user identity of the recipient user. A setup request to establish the communication event is sent over the first communication system from a first initiator client to a first recipient client. A communication event is authorized to proceed over the first communication system on the basis that the initiator user and the recipient user are contacts within the second communication system.

Abstract: Methods and computer program products for establishing communication events between an initiator user and a recipient user over a first communication system. The initiator and recipient users are contacts within a second communication system but are not contacts within the first communication system. For the initiator and recipient users, an association between a first user identity in the first communication system and a second user identity in the second communication system is determined. The initiator user device uses the association for the recipient user to determine the first user identity of the recipient user. A setup request to establish the communication event is sent over the first communication system from a first initiator client to a first recipient client. A communication event is authorized to proceed over the first communication system on the basis that the initiator user and the recipient user are contacts within the second communication system.

Abstract: Methods and computer program products for establishing communication events between an initiator user and a recipient user over a first communication system. The initiator and recipient users are contacts within a second communication system but are not contacts within the first communication system. For the initiator and recipient users, an association between a first user identity in the first communication system and a second user identity in the second communication system is determined. The initiator user device uses the association for the recipient user to determine the first user identity of the recipient user. A setup request to establish the communication event is sent over the first communication system from a first initiator client to a first recipient client. A communication event is authorized to proceed over the first communication system on the basis that the initiator user and the recipient user are contacts within the second communication system.

Abstract: A voice or video call is to be established between a caller and a callee based on a call flow that involves a call establishment request and a corresponding call acceptance response. A first call establishment request is sent to a called terminal (of the callee) that is unready to accept the call upon receiving this first call establishment request. Once the called terminal is ready to accept the call, instead of the call acceptance response, a reverse call establishment request for the call is received back from the called terminal. The reverse call establishment request is automatically accepted on behalf of the caller on condition that the reverse call establishment request was received back from the called terminal within a certain time limit. If so, the call is accepted by sending an instance of the call acceptance response to called terminal.

Abstract: A voice or video call is to be established between a caller and a callee based on a call flow that involves a call establishment request and a corresponding call acceptance response. A first call establishment request is sent to a called terminal (of the callee) that is unready to accept the call upon receiving this first call establishment request. Once the called terminal is ready to accept the call, instead of the call acceptance response, a reverse call establishment request for the call is received back from the called terminal. The reverse call establishment request is automatically accepted on behalf of the caller on condition that the reverse call establishment request was received back from the called terminal within a certain time limit. If so, the call is accepted by sending an instance of the call acceptance response to called terminal.

Abstract: A voice or video call is to be established between a caller and a callee based on a call flow that involves a call establishment request and a corresponding call acceptance response. A first call establishment request is sent to a called terminal (of the callee) that is unready to accept the call upon receiving this first call establishment request. Once the called terminal is ready to accept the call, instead of the call acceptance response, a reverse call establishment request for the call is received back from the called terminal. The reverse call establishment request is automatically accepted on behalf of the caller on condition that the reverse call establishment request was received back from the called terminal within a certain time limit. If so, the call is accepted by sending an instance of the call acceptance response to called terminal.

Abstract: Methods and computer program products for establishing communication events between an initiator user and a recipient user over a first communication system. The initiator and recipient users are contacts within a second communication system but are not contacts within the first communication system. For the initiator and recipient users, an association between a first user identity in the first communication system and a second user identity in the second communication system is determined. The initiator user device uses the association for the recipient user to determine the first user identity of the recipient user. A setup request to establish the communication event is sent over the first communication system from a first initiator client to a first recipient client. A communication event is authorized to proceed over the first communication system on the basis that the initiator user and the recipient user are contacts within the second communication system.