There are prepaid phones and postpaid phones. Prepaid phones can be pay as you go SIM deals with charges per minute of calling, per text and per megabyte or kilobyte of data. The SIM card may be free or you may have to pay for it. Prepaid phones may also have monthly plans. In such cases, you may get the SIM card for free and you will have the option to choose unlimited deals. You can get unlimited minutes, texts and even unlimited data which will be capped up to a certain usage on high speeds or more advanced networks like 3G and 4G LTE. Postpaid phones are mostly contracts. There are some plans that are postpaid but you don’t have to sign up for twelve months or two year contracts.

Now, within the realm of pay as you go SIM deals or prepaid phones, you will come across two terms. One is unlocked and the other is SIM free. Both unlocked and SIM free phones can work with prepaid monthly plans or pay as you go deals which is also prepaid. But they are not the same or identical.

• Unlocked phones imply that they have no allegiance to any network. They can be used on absolutely any network and you can go for pay as you go SIM deals from any reseller of the major networks. Pay as you go SIM free phones doesn’t have the same implication. SIM free phones can work with any SIM card but that is in theory. It may not be compatible with a network you choose.

• Unlocked phones were once tied up with one network or made to work with chosen networks. But after being unlocked, they can work with all pay as you go SIM deals. SIM free phones may have preferences. They may only work with certain networks. For instance, the SIM free phones may only work with the major networks or a few resellers of the major networks. They may work on certain frequencies or a certain network, which could be 2G, 3G or 4G. It is quite possible that SIM free phones will work on the 3G network of the same carrier but not on the 4G LTE network. And this is not because the SIM card is not compatible but because the phone is not compatible.
Always read the fine print while shopping for pay as you go SIM free phones and subsequently choose the appropriate pay as you go SIM deals.