A method carried out by a telephony application server (TAS) is described that facilitates handling a digital voice network media resource reservation request failure notification, issued by a call session control function, arising from a connection request from an originating mobile user equipment to a terminating mobile user equipment. The method includes the TAS receiving a connection request response message including the digital voice network connection request failure notification. The TAS detects a media resource reservation request failure error condition based on the connection request response message containing the digital voice network media resource reservation request failure notification. Thereafter, the TAS issues a configured error response message to initiate an alternative message connection between the originating mobile user equipment and a message file service, where the message file service comprises an interface facilitating receiving a message from the originating mobile user equipment to the terminating mobile user equipment.