[arm-allstar] registration

[gm4upx at gb7jd.co.uk]

I have 4 public nodes over three devices with 3 different bind ports 
configured in allstarlink.org with the corresponding ports as bind ports 
in iax.conf.

Today I notice that my registration of all 4 nodes is being rejected and 
the response is port 4569, regardless of port configuration.

My nodes appear in the lists of online nodes and also appear to be 
working as normal.

So my question is :-  what exactly is the purpose of the registration ?

Regards,
Ian..