I was playing around with the ctd.sh script and my SER setup w/ ATA-186 clients. I got it to work by adding a simple "ACK" to the ctd script after the INVITE response and before the REFER. The documentation page indicates that this ACK happens in the ctd example, but running a tcpdump/ngrep on the SER machine showed that it never did. The only problem I have is that when I send an ack through the fifo, it looks like SER is waiting for a response, so it takes a good 20 seconds or so before it gives up and moves onto the REFER. Is there an easy way to convince SER to not wait for a response to an ACK through the FIFO? I thought there was a fifo command to do this but couldn't find one... Also for anybody who cares, the REFER method works with the ATA-186 firmware 2.16 and higher, but I also created a modified version of the ctd script that completed the calls using the BYE/Also method that works on pre-2.16 ATAs. - Mike