If you run into issues while making calls, it is of great help to check Asterisk logs for any errors that might cause the problem that you are experiencing.
If something like that happens, logs are found in the following folder:
Main log file to look at is messages log file located in above folder. It contains information printed out in asterisk CLI which can include errors, warnings and notices.
Using standard Linux text processing commands like cat, tail, grep, you can go through your messages file more easily in situations where that file is grown to several and more hundereds of megabytes.