we have an UC520 with an ISDN- BRI connection.
At one analog port of the UC we connect a fax device. the problem is following: the fax device can receive fax only if it send a fax before.
after sending a fax, the device receive faxes by some time. after that, the problem occurs again.
the customer say, the fax device worked fine at a other location before. the customer also switch the device with another, without success. so he means, that the configuration of the UC is incorrect. but if we connect an analog phone at the port of the fax device, it works free of errors. somebody there, how heard this problem?