Yezz Classic C21 Handbuch Seite 76

To add another connection, repeat all the steps.
Configure the browser
Once the connection is added, you need to configure the
Internet browser:
1. In Menu mode, select Services → Internet service →
Settings → Data account, select the SIM card (if necessary)
and choose the connection created in the previous step.
Switch between carriers
(SIM cards)
If you use multiple SIM cards and want to switch to another
one, follow this steps:
1. Configure the connection for both SIM cards (refer to "Add
a new connection").
2. In Menu mode, select Services → Internet service →
Settings → Select profile and choose SIM1 or SIM2
according your necessities.
Is possible to select Always ask, then the browser will ask
which SIM you want to use before start the Internet session.