There are two ways to pass VoIP calls to a GSM network:
- Direct connection to a GSM operator using VoIP or PRI – the way is usually more expensive.
- Using your own GSM gateways with SIM cards of the GSM operator.
Usually GSM gateway-based solution is more profitable and flexible. Here are some advantages of owning a GSM gateway.
- Very flexible system – you can increase or decrease your capacity in minutes.
- Lower costs – you can manage your costs easily with your own SIM cards.
- Manageable traffic quality – you can monitor your traffic quality parameters like ASR, ACD etc.
- Less operation procedures – you are all by yourself with your traffic.
There are two technical solutions to access GSM network from VoIP using own GSM gateways: standalone GSM gateway described below and SIM server-based solution.
GSM gateway purpose is to interconnect GSM networks with others (like PSTN or VoIP networks). In case of standalone GSM gateway call flow will look like:
A GSM gateway usually has two interfaces: Ethernet to access VoIP network and GSM module to access GSM network. There are SIM cards inserted into the GSM module inside the gateway.
Standalone gateways are cheap, but they have lots of disadvantages also:
- Standalone gateways have more simple management interface and not as brilliant as SIM server interface. It is still easy to use but with much less functions.
- It’s hard to maintain lots of standalone gateways located in different places – you can not replace SIM cards fast and frequently.
- If you are using more than one gateway it’s hard to change their configuration synchronously in the same way at the same time.
- There is a limited SIM cards capacity on standalone gateways. Mostly companies which do not replace the SIM cards and using postpaid solutions are using this. Generally there are not more than 4 SIM cards per GSM Port.
- Since standalone gateway uses one SIM card to terminate lots of calls continuously, the traffic might be treated by a mobile operator as abuse and appropriate SIM cards will be blocked in the case.
- If you are using a standalone GSM gateway you can not use same SIM Cards on different locations spontaneously – have to move the SIM cards physically between your gateways.
- You can not get all advantages of a Human Behavior System to simulate SIM usage by a human.
- No chance to replace any faulty SIM card with a working one automatically without a physical access to the gateway.
- You won’t be able to allocate SIM cards with standalone gateways according to your operation model.
That is why we recommend to use SIM server-based solution instead.