It's not required to have mgetty to answer phone calls. From version 2.04 DayDream has been able to answer phonecalls by itself. Run DayDream with command line parameter daydream -n <node>. Note that you need a console or xterm to run a node. Modem is configured in $DAYDREAM/configs/modem<node>.cfg.
See example modem1.cfg, it is quite self-explanatory.
DDSnoop is not supported on nodes that are answering the calls by themselves.
It's not advicable to make DD answer the phonecalls. If DD crashes, it dies and there's nothing that will answer the phone after this.
This is just for those who are too stupid to configure mgetty correctly :)
If DD says that it can't open serial port, make sure user bbs can access /dev/tty?? of the node.