Lidl

[inquisitor]

Originally Posted by thermos

- activate the SIM card either via on-line or SMS

You can't activate the SIM by SMS as it won't register on the network before it has been activated. You can only activate the SIM online or through the printed form which you would need to submit by snail mail or fax and would take at least 24h to be processed

- book the 30 days unlimited plan (14.99 Euro) by on-line page. or I can make it by SMS or other ways?

As described in detail here you can also subscribe to the monthly data flat by sending a text with "START MONATSFLAT" to 54356 (L-I-D-L-M). Shortly after that you should receive a text asking for confirmation which you need to answer by sending just "JA". Before starting to browse the internet make sure you've received the final confirmation from Lidl saying that your "Monatsflatrate" has been successfully activated.

One other thing, can I use the remaining money (10 + 15 - 14.99) for local call?

Sure. you can call all German networks (no matter if landlines or mobiles) at € 0.09/min. Calls to the US, Canada and European landlines are charged at the same price while calls to European mobiles cost € 0.29/min.
You should know that as mentioned here under "activation", step 7 you can get a bonus credit of € 5 if you provide some other Lidl customer's phone number as referer during activation. The instructions contain such number (actually mine ) and the refering customer does also receive a bonus of € 5. The problem is just that it may take up to 3 weeks until this bonus from the referral program has been accredited so you would need to make sure your SIM is being activated 3 weeks before arrival so you would have a total credit of € 15 which would suffice for the monthly data flatrate.