Communication failover in a distributed network

A system comprising:

• a communication server that:
• receives an initial request, from a second communication device, to establish a communication session with a first communication device across a primary network, wherein the initial request comprises a first communication address of the first communication device;
• detects that the communication session across the primary network cannot be established;
• causes the initial request to be transformed into a changed request, in the changed request the first communication address in the initial request is transformed to a second communication address in response to detecting that the communication session across the primary network cannot be established,
• wherein the changed request contains a parameter that indicates that the changed request is to be sent via the secondary network;
• and
• sends the changed request with at least the second communication address to a gateway to establish the communication session across a secondary network, wherein the gateway sends the first communication address in a portion of the communication session using Dual-Tone-Multi-Frequency (DTMF) and completes establishment of the communication session using the second communication address.

A gateway, comprising:

• a processor that:
• receives an initial request, from a second communication device, to establish a communication session with a first communication device across a primary network, wherein the initial request comprises a first communication address of the first communication device;
• transmits the initial request to a communication server;
• in response to a determination that the communication session across the primary network cannot be established, receives a changed request derived from the initial request, wherein the first communication address in the initial request is transformed to a second communication address in the changed request and wherein the changed request contains a parameter that indicates that the changed request is to be sent via the secondary network;
• establishes a portion of the communication session;
• sends the first communication address in the portion of the communication session using Dual-Tone-Multi-Frequency (DTMF) signaling;
• and
• completes establishment of the communication session using the second communication address.