An initial request is received to establish a communication session. The initial request contains a communication address of a first communication device. A communication server detects that the communication session cannot be established across a primary network. In response, the initial request is repurposed by changing the first communication address to a second communication address. The changed request is sent to a communication system, which adds a field to the changed request that indicates that the changed request is to be sent via a secondary network. The changed request is sent with the field to the communication server. The changed request with the second communication address is sent to a gateway to establish the communication session across a secondary network. A portion of the communication session is established using the second communication address. The first communication address is sent in the portion of the communication session using Dual-Tone-Multi-Frequency (DTMF).