Description:
I'm trying to use my old Nokia 6021 as bluetooth modem. After updating to bluez5 I'm getting the next error message in gnome-bluetooth GUI:
Method "Connect" with signature "s" on interface "org.bluez.Serial" doesn't exist

According to Bluetooth_GPRS_Howto in archwiki I tried configuring it via command line.
As /etc/bluetooth/rfcomm.conf doesn't exists for bluez5 I used the next command to create rf binding:
rfcomm bind hci0 <phone bluetooth MAC>
And it worked for bluez 5.9 and linux 3.11.

Recently I updated to bluez 5.12 and linux 3.12. And RF binding stopped working.


Additional info:
* package versions:
bluez 5.12
linux 3.12.5
gnome-bluetooth 3.10.0

* config and/or log files:

Steps to reproduce:
1)
- Pair Nokia series 40 phone via bluetooth.
- Check "Connect to internet using DUN"
- Verify that the next message appears in system journal:
gnome-session[1449]: ** (gnome-control-center:1751): WARNING **: dun_connect_cb: DUN error: Method "Connect" with signature "s" on interface "org.bluez.Serial" doesn't exist


2)
- Create RF binding with command:
rfcomm bind hci0 <phone bluetooth MAC>
- Connect to internet with wvdial specifying modem /dev/rfcomm.
- Verify that output is the following:
--> WvDial: Internet dialer version 1.61
--> Cannot get information for serial port.
...
--> Cannot open /dev/rfcomm0: Transport endpoint is not connected

Also the next messages I found if system journal:
kernel: Bluetooth: TIOCGSERIAL is not supported

I'll provide any additional information if needed.