Dial plan transparency for fragmented networks

In an enterprise network having geographically dislocated first and second network regions, wherein the first and second network regions are in communication with one another through first and second intermediate networks, wherein the first network region comprises a first gateway, a first media server, and a plurality of communication devices, wherein the second network region comprises a second gateway and a voice mail server, wherein each of the first and second intermediate networks has a corresponding unique telephone number, each of the telephone numbers being associated with a plurality of subscribers, and wherein, in a first operational mode, the first and second network regions are controlled by the first media server and at least most of the bearer channels for live voice communications are routed over the first intermediate network and wherein, in a second operational mode, the first media sever does not control the second network region, a method comprising:

• (a) determining, by the first network region, that call coverage requires a contact from a first communication device to be directed to the voice mail server to permit the user of the first communication device to leave a voice message for a subscriber;
• (b) determining, by the first network region, that the enterprise network is in the second operational mode;
• (c) initiating, by the first network region and over the second intermediate network, a call to the unique telephone number corresponding to the second network region;
• (d) upon successful termination of the call on the second network region, in-band signaling, over a channel of the call, an identifier of the voice mail server;
• and
• (e) thereafter connecting, over the call channel, the first communication device with the voice mail server.

An enterprise network, comprising:

• (a) a first network region geographically dislocated from a second network region, wherein the first and second network regions are in communication with one another through first and second intermediate networks;
• (b) a first gateway in the first network region, wherein the second network region comprises a second gateway;
• (c) a first plurality of communication devices in the first network region, wherein the second network region comprises a second plurality of communication devices;
• (d) a primary media server operable to control the first and second network regions in a first operational mode but not in a second operational mode;
• wherein bearer channels for at least substantially real-time communications are routed over the first intermediate network;
• and
• (e) an inter-gateway routing agent operable, in the second operable mode and in response to a request, by a first communication device of a first subscriber in the first network region, to set up a call with a second communication device of a second subscriber in the second network region, (i) to set up a call, over the second intermediate network, to a second telephone address, the second telephone address being associated generally with the second network region and not with a particular subscriber, and (ii) to transmit over a channel of the call a unique identifier associated with at least one of the second communication device and second subscriber.

An enterprise network, comprising:

• (a) a first network region geographically dislocated from a second network region, wherein the first and second network regions are in communication with one another through first and second intermediate networks;
• (b) a first gateway in the first network region, the first gateway being in communication with a second gateway in the second network region;
• (c) a first plurality of communication devices in the first network region, the first plurality of communication devices being in communication with a second plurality of communication devices in the second network region;
• (d) an inter-gateway routing agent operable to:
• (i) determine, in response to a request, by a first communication device of a first subscriber in the first network region, to set up a call with a second communication device of a second subscriber in the second network region, that, due to a predetermined condition, the call must be set up over the second intermediate network and not the first intermediate network, wherein the predetermined condition is at least one of a desired quality and/or grade of service is currently not available over the first intermediate network and a primary media server in the first network region has lost control of the second network region, (ii) to set up a call, over the second intermediate network, to a second telephone address, the second telephone address being associated generally with the second network region and not with a particular subscriber, and (iii) to transmit over a channel of the call a unique identifier associated with at least one of the second communication device and second subscriber.