If you have configured several internet telephone numbers in the FRITZ!Box, you can conduct up to five internet calls over the FRITZ!Box at the same time.

If you cannot conduct more than one call, either the throughput of the line is not sufficient (each call requires 128 kbit/s upstream and downstream) or your provider does not allow you to conduct several calls at the same time.

Note:The FRITZ!Box's DECT base station allows you to conduct up to three calls at the same time. A maximum of two calls can be conducted at the same time using IP telephones.