Here are the settings for a VM SIM in a datacard
These settings I collected and tested can be found in the first 'sticky' thread in this Cell C/Virgin forum. To make it easy however here they are again. They work for me, but your mileage may vary....
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USING A GPRS DATACARD WITH A VIRGIN SIMCARD:
A separate Virgin profile needs to be set in the software (e.g. Vodafone's Dashboard 7, which works with any network, not just Voda).
Creating a new profile should automatically also create a connection entry and icon in Windows' Network Connections, though you should never need to work through that icon if you are using connection software such as the Dashboard.
If settings do not pick up automatically the following are valid for Virgin (note that after creating the profile in the Dashboard, you will have to Finish and then re-edit it during a second pass to get to where you can enter the APN, and in another section the Internet Protocols -- these options are not available when you first create a Profile).
APN: vdata
Login ID: blank
Login Password: blank
DNS: 196.31.116.241 and 196.31.116.242
(Generic public addresses which will work are 196.7.0.138 and 196.7.142.132 but may be slower than the correct ones)
SMTP server for your outgoing mail (change in e-mail client): mail.cmobile.co.za
Modem setting: officially should be *99#, but also appears to work retaining Voda setting (as does MTN: *99***1#)
Initialization string might need to be changed to at+cgdcont=1,"ip","vdata","",0,0,
(but also appears to work retaining Voda setting at+cgdcont=1,"IP","internet"
Current flat data rate 50c/MB on all credit or prepaid plans (no data bundles)
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Good luck! Trust me, at 50c/MB it's worth a little configuration hassle!