A method for active mobile collaboration performed in a mobile communication system (100, 200, 300, 400, 500, 550, 600 and 700) that uses a loosely-coupled client-server architecture, the system including a facilitator acting as a server, serving a plurality of mobile communication devices running a client application, the method comprising: the facilitator transferring context information for a plurality of target mobile devices to a calling device of a caller, wherein the context information includes at least one of a connectivity state and an availability profile of each of the plurality of target mobile devices, wherein the connectivity state of a target mobile device includes at least one of a reachable state and an unreachable state, wherein the target mobile device is in a reachable state when the target mobile device is in a powered state and connected to a corresponding communication network, and wherein the target mobile device is in an unreachable state when the target mobile device is at least one of in an un-powered state, disconnected from the communication network, and engaged in a voice call; after receiving the context information, selecting, from the plurality of target mobile devices, at least one recipient associated with at least one target mobile device selected to receive a voice call from the caller using the calling device, generating a call request at the calling device, and sending the call request to the facilitator; in accordance with the context information of both the selected at least one target mobile device and the calling device indicating a reachable state, the facilitator delivering the call request from the calling device to the selected at least one target mobile device of the selected at least one recipient via a data coupling; the facilitator providing a delivery confirmation to the caller at the calling device in response to delivery of the transferred call request to the selected at least one target mobile device; generating a plurality of response options on the selected at least one target mobile device in response to receipt of the call request from the facilitator, wherein the response options include at least one of accepting the call request, postponing the call request, generating a return data message including at least one of a text message and a voice message to the calling device, and initiating the voice call; and generating a response message in response to selection of a response option by the recipient on the selected at least one target mobile device, and the facilitator transferring the response message to the calling device over the data coupling. the facilitator transferring context information for a plurality of target mobile devices to a calling device of a caller, wherein the context information includes at least one of a connectivity state and an availability profile of each of the plurality of target mobile devices, wherein the connectivity state of a target mobile device includes at least one of a reachable state and an unreachable state, wherein the target mobile device is in a reachable state when the target mobile device is in a powered state and connected to a corresponding communication network, and wherein the target mobile device is in an unreachable state when the target mobile device is at least one of in an un-powered state, disconnected from the communication network, and engaged in a voice call; after receiving the context information, selecting, from the plurality of target mobile devices, at least one recipient associated with at least one target mobile device selected to receive a voice call from the caller using the calling device, generating a call request at the calling device, and sending the call request to the facilitator; in accordance with the context information of both the selected at least one target mobile device and the calling device indicating a reachable state, the facilitator delivering the call request from the calling device to the selected at least one target mobile device of the selected at least one recipient via a data coupling; the facilitator providing a delivery confirmation to the caller at the calling device in response to delivery of the transferred call request to the selected at least one target mobile device; generating a plurality of response options on the selected at least one target mobile device in response to receipt of the call request from the facilitator, wherein the response options include at least one of accepting the call request, postponing the call request, generating a return data message including at least one of a text message and a voice message to the calling device, and initiating the voice call; and generating a response message in response to selection of a response option by the recipient on the selected at least one target mobile device, and the facilitator transferring the response message to the calling device over the data coupling.