Mercedes-Benz GLA Series Operator's Manual page 221

®
Irrespective of this, Bluetooth audio functional‐
ity can by used with any mobile radio unit.
For information on the range of functions of the
mobile radio unit to be connected, see the man‐
ufacturer's operating instructions.
Network connection:
The following cases can lead to the call being
disconnected while the vehicle is in motion:
You switch into a transmission/reception
R
station, in which no communication channel
is free.
The SIM card used is not compatible with the
R
network available
a mobile phone with "Twincard" is logged into
R
the network with the second SIM card at the
same time
The multimedia system supports calls in HD
®
Voice for improved speech quality. A require‐
ment for this is that the mobile phone and the
mobile phone network provider of the person
®
you are calling support HD Voice .
Depending on the quality of the connection, the
voice quality may fluctuate.
Further information can be obtained from an
authorized Mercedes-Benz Center or at:
https://www.mercedes-benz.com/connect
MBUX multimedia system 219