Two udp ports one freepbx

Hi all. I have a bit of an unusual situation.

My setup consists of a Grandstream HT818 ATA with 5 modems attached. Line 1-4 are regular USR for the United States and Line 7 contains a UK modem connected with an rj11 cable and rj11 to BT adapter. It dials out just fine.

However, I want line 7 to receive a UK ring tone rather than a US one. Easy enough I thought, the ATA has 2 profiles. Profile 1 is used for my US modems and connects to my freepbx no problem.

I have configured the 2nd problem with the UK ringtone cadence, however it tells me that the SIP port is already in use. Obvious, I guess. My question is, how do I get my freepbx to use a different port for this second profile.

To round up, I have 2 SIP lines, one from a US provider and one UK with a local dialin only number.

Freepbx isn’t my day to day job, just a hobby so I’m sure there’s someone who had come across this and more familiar than I. Any help would be appreciated.

Thanks,