Something that you also have to know when it comes to SIM Gateways is that the usage is capped. The advantage to using a capped line is obvious is you are thinking of cost of course. Since the usage is capped, it means that you can effectively control the money you are spending while still enjoying the benefits of the service. This is especially useful if you are trying to work within a fixed budget because it allows you to stick within that fixed budget.
Calls aren’t the only way that you can save money on your bill with a SIM Gateway though. Since SIMs can be used to send SMS messages, you can effectively save money there too because text messages are much cheaper to send than making phone calls. On a separate note, the good thing about text messages is also that you have proof of conversations right off the bat rather than having to record what you are saying.
Ultimately, if your goal is to save money then a SIM Gateway will be one of the best things you can get to save money. Make sure you try the product from trusted manufacturers.