[Freeswitch-users] Querying presence from third party SIP platform

Hi All we are using Freeswitch typically to add feature to our core platform in particular around queuing with mod_fifo. we have come up against an issue whereby the FS does not have visibility of the state of the phones as they are registered on another sip platform. I was wondering if there was a way for FS to send SUBSCRIBE messages out through a SIP trunk to the other platform to query the state of the lines? any help is very welcome thanks marc