A method and apparatus for maintaining a communication link through a NAT or other boundary device. Keep-alive messages (keep-alives) are transmitted and received by the boundary device to maintain the link therethrough. Address information of a keep-alive purports that keep-alive has traversed or is to traverse a predetermined portion of the communication link, such as a wireless “over the air” portion. However, the keep-alive is inhibited from traversing the predetermined portion. This may be accomplished by one or more of: spoofing the origin of the keep-alive such that it only appears to have traversed the predetermined portion; and causing the keep-alive to be discarded before traversal of the predetermined portion. Discard may be facilitated by configuration of the TTL field of the keep-alive or by use of a filtering device.