CME error: 34883

I am trying to configure a Q2406B in ftp mode but the commands AT#APNSERV, AT#FTPUN and AT#FTPPW always return
the following message: +CME ERROR: 34883. The connection is ok, ping command works.
Could anyone help me?
Regards, Evandro.

It´s seens one need to pay to access and use the services of the 7th tcp/ip layer.