VIP-281gs – as a GSM Gateway

I set VoIP Basic users and password options in VIP-281gs, but when I tried to register from X-LITE I receive:
Registration error – 481, I have no idea what is wrong?
What do you think using freePBX will I be able to do outgoing calls using VIP-281gs?

So I have freePBX Stable-2.210.62-3 and I would like to use a VIP-281gs as a GSM Gateway for outgoing calls.
Manual for it is here:
Do you know how to configure it?

I am sure it will work, SIP is a standard. If you are getting a 481 error from x-lite you are probably trying to register to your gateway. A gateway is a SIP B2BUA and doesn’t accept registrations.

I thought that freepbx should be registered to VIP-281gs similar to other paid services to that I can registered from X-LITE or from freepbx and use it.

So you suggest that VIP-281gs should be registered in freepbx?

It does not need to be registered at all unless you plan on using a dynamic IP address.

The device must peer with FreePBX as a trunk. Then it can be used for inbound and outbound calls.

Suggest perhaps an introduction to how SIP works may help: