Dial() ignoring long commands

I’m using the Dial-command to call about 20 phones simultaniously.
I’m using Asterisk 11 on a Ubuntu 14.04.1.
When I try to Dial(SIP/phone1&SIP/phone2&…) then a few phones doesn’t ring (the last ones). When I used asterisk -rvvvvv to debug my code, I realized, that the command, that get’s print in the console is not the whole Dial-command but only the half of it. I therefore expect asterisk to only interpret the first X characters in each line of dialplans.
Is this the default behaviour and/or is this really the intended behaviour.
Thank you very much for your replies :smile: