Have anyone successfully connected 2 DSXs with voip boards?
I followed manual from nec site dated 2011 and according to system status page from both sites they are registered, but I’m unable to make any calls between.
I set 8 X-lite softphones at Site 2 awhile ago and they never had issues with them, other thaninconvenience of having desktop phone and soft phone at the same desk. Main reason for this setup is to deliver available pri lines to site 2 from site 1 for outbound calls

Both DSXs are on the same network thru site to site Vpn.

Site1(remote):
Dsx160 has a 23 channel pri and 16port voip board
Extensions 402-409 set as sip trunks

Site 2(local):
Dsx80 has 8 co lines and 8port voip board
Provider is set to DSX SIP, to lines 33-40 (unused Pri card occupies lines 9-32)

In theory if I dial extension 402 from site 1 it should ring line 33 at site 2, instead I get an announcement that extension 402 is busy

Anyone seen more recent manuals?
https://www.necdsx.com/docs/files/sip_trunking/dsx_sip_setup_1.04.pdf

Screen shots of setup
https://www.dropbox.com/sh/xgkpta0kozcm5m5/AABW4S_MtArkspSBCndoLlu9a?dl=0
https://www.dropbox.com/l/scl/AACLodRF0JkxeE2qO45fhW-tY1HEfvYs1h0

After updating both sites to latest firmware 3.46 I’m able to make outbound and intercom calls from site 2 through Sip trunks 402-409.
However from site 1 to site 2 calls don’t go thru.
On the station at site 1 I set hotline keys for extensions 402-409 and when I call these extensions it blinks green for half a second and than announces that this extension is busy.
Any idea what’s causing the call to terminate?

Might me a timer issue, you'll have to navigate programming and do the trial and error method.