Present disclosure relates to system and method for providing SIP trunk service to at least one telephone system by an application server over a network, comprising establishing a connection between at least one telephone system and a first network entity via a first access node, and availing at least one SIP trunk service. Next, the at least one telephone system dynamically checks connectivity with the first network entity. The at least one telephone system establishes a connection with a second network entity via a second access node, in an event the connectivity with the first network entity fails and transmits a signal request to the application server. The application server processes the signal request and provides the at least one SIP trunk service to the at least one telephone system.