This attribute indicates the current modem algorithm(s) active for
the channel. This attribute has one of the following values:
t30: T.30 is active. T.30 is the Group 3 fax protocol.
v17: V.17 is active.V.17 is an ITU-T 14400bit/s modem standard.
v21: V.21 is active. V.21 is an ITU-4 300bit/s modem standard.
v22: V.22 ia active. V.22 is an ITU-T modem standard that operates
at 1200bit/s and 600 baud.
v22bis: V.22bis is active. V.22bis is an ITU-T modem standard that
operates at 2400bit/s and 600 baud.
v27ter: V.27ter is active. V.27ter is an ITU-T 7200bit/s modem
standard.
v29: V.29 is active. V.29 is an ITU-T 9600bit/s modem standard.
v32: V.32 is active. V.32 is an ITU-T modem standard that operates
at 9600bit/s and 2400 baud.
v32bis: V.32bis is an ITU-T modem standard that operates at a
speed of 14.4kbit/s.
Description of bits:
t30(0)
v17(1)
v21(2)
v22(3)
v22bis(4)
v27ter(5)
v29(6)
v32(7)
v32bis(8)