Acer Liquid Z220 Duo User Manual page 62

62 - Managing your SIM cards
Limitations when using multiple SIMs
When a SIM is:
In a call
Ringing
Sending or receiving a message
Using a data connection
Note
If you are using data on one SIM and you make or receive a call, or send or
receive a text message on another SIM, the first SIM's data connection will
be temporarily halted.
Other SIMs cannot:
Dial out
Receive a call (caller will get a
"number not available" message)
Send or receive a message
Use a data connection