1. A method for operating a gateway mobile switching center (GMSC) to execute an emergency callback to a mobile device, the method comprising: processing, at a GMSC, an emergency callback received from a public safety answering point (PSAP) in response to an unexpected release of an emergency call to reestablish communication between the PSAP and the mobile device; the GMSC issuing a special-use SendRoutingInformation (SRI) message to a home location register (HLR), the special-use SRI message comprising a parameter to suppress a call blocking feature enabled for a calling party of the emergency call; the GMSC processing an SRI response message received from the HLR in response to the special-use SRI message, the SRI response message comprising a Mobile Station Roaming Number (MSRN); and the GMSC routing the emergency callback to a servicing mobile switching center (MSC) based upon the MSRN.