Finally, I found some time to type a few words more .
About bonus top-ups in Play: it's not so good - they can be used only for national calls, SMS, MMS and data (and not premium rate services of course). Moreover, they last for 30 days only - if you don't want to lose the bonus subcredit (called "Premia") you must make a large top-up with another bonus (min 50 PLN) before expiration of the previous bonus.
The reward for incoming calls is 1 minute of outgoing national calls for each 2 FULL minutes of a single incoming call (from any operator, but not in roaming).
Each reward is valid for 30 days since the incoming call.
The usage order/sequence of credits (where applicable) is
1. Rewards for incoming calls
2. Premia bonus top-ups
3. Main credit
Play offers with the first prepaid in Poland with the full spport of services like call waiting, call barring, conference calls, call diverting to any number.
The bad thing is when the outgoing calls expire, the main credit as well as "subcredits" are all lost
.
Data connections are happily available not only for WAP but also for "normal" Internet.
To summarise, it's a good voice/SMS offer from the operator which considers itself to be a "multimedia" one
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I sent details to Effendi so that he could update the page...