asterisk users - May 2005 - Voice Transfer of a Call Works only in One Way

Hello,

Need your support for my following problem.

I am using Asterisk to switch calls from softphones to our internal
telephone network which is connected to the Asterisk server via an ISDN
Fritz card. If I build up a call from a softphone to our internal network,
voice is broadcasted only in one way from the external network to the
softphone. Voice transfer from the softphone to the subscriber of the
external network is not possible, except the first connection after a
reboot of my Linux server on which Asterisk is running.

Many thanks in advance for your attention to my enquiry.

Best regards,

Martin