I buy SIMs for my multiple clients – which is the best approach?

As each of your clients may require different benefits and conditions, including different connectivity methods it is best to request a different offer for each client. In this way you will be able to assign specific benefits, and label to a group of SIM cards pertaining to each client. This will also give you the ability to easily monitor the performance of each customer project individually.

This is completely up to you. If you have different clients but all operate under same conditions you may buy one Offer with same conditions and simply add more SIMs for each customer. In this approach you can label each SIM individually and apply filters in your SIM inventory to monitor specific clients. All SIMs in the same Offer will then use same benefits and share from same pool of data or SMS.