A method and system for authenticating a communication device with an application server. The application server includes a gateway registration port, a gateway server port, and an electronic processor. The electronic processor is configured to receive, via the gateway registration port, a registration request, including a unique identifier, from a first device over a first communications network that operates in accordance with a first modality and receive, at the gateway server port, an access request including an identifier from an unknown device over a second communications network that operates in accordance with a second modality. The electronic processor is configured to compare the second identifier with the first identifier to determine if the identifiers match, grant the unknown device access when the identifiers match, and deny the unknown device access when the identifiers do not match.