We're having some issues with a Netcomm Roaster II Ultra 56k modem (serial) connected to our SBS 2011 server (migrated from SBS 2008). We have Windows Fax Server configured and it's receiving incoming faxes with no issues. These are then being routed to a public folder on Exchange, all OK so far.
We're having no end of trouble sending out though using Windows Fax and Scan. We've tested sending to a couple of different numbers and devices. The modem dials out and when it starts to transmit data it drops the connection. On the receiving devices it shows the incoming connection, answers it and states receiving. After 5-10 seconds it drops (and one device - a Brother MFC - shows Comm.Error).
I don't believe there is an issue on the line as it can receive faxes with no worries and I can call out on the line OK. The modem is installed with Windows drivers (standard 56k modem) as we were unable to find any Netcomm drivers when setting it up a few months ago.
Does this sound like a device or driver error or something else again?