Exit code 156 is defined as “Failure to setup NIC control” (see the Detailed Installation Guide for the meaning of all exit code). This means that the NIC you have told HAAst to use (in the [voipnic] stanza of haast.conf) is not responding as expected or not available.
If you set the log level to DEBUG and restart HAAst, you will see more details of what is going wrong in the haast log file. Most often this relates to configuring HAAst to use an IP address that is already in use somewhere on the network, or use an interface that is not present in the system (possibly due to a typo in the interface name). If you post the [voipnic] stanza of your haast.conf, and the output of ifconfig we can offer more specific advice.
