I ask your help for a strange situation with topos, 183 (before a 200OK) and SIP INFO

My topology is kamailio in front of asterisks; so kamailio has 2 interfaces (1Public to talk with customers and carriers and 1 Private to talk with asterisk).

In the image:

- the first column is the customer

- the second is the public interface of kamailio

- the third is the private interface of kamaiio

- the fourth is asterisk

As you can see in the image, the customer send an INVITE and the carrier give back the IVR messages in a 183 (before a 200OK) asking for an IVR selection.

The customer (configured to use SIP INFO) types a key and sends in INFO, but as you can see kamailio sends the INFO to himself to private interface instead of sending it to asterisk as if the contact that handled topos contained incorrect information.

- If the customer is configured with a RFC2833 

- or if the IVR messages is not in a 183 but is sent after a 200OK 

- or if I disabe TOPOS

I used kamailio 5.5.3, I also try to upgrade to 5.5.4 but nothing change

Maybe could be connected with 

Could be a kamailio bug for this particular situation or am I getting lost in a glass of water?

thanks a lot

cheers