Remote extensions works but no voice

My set up is as follows:

SPA3102 PSTN Line ------ FreePBX ----- || -------------- Ext 3002 (X-Lite)
(SIP 5061) (SIP 5091) Router
|
SPA3102 Line 1 ext 3003-----
(SIP 5060)

My X-Lite at extension 3002 can call out via the Sipura ATA. Incoming calls from the Sipura PSTN Line are routed to ext 3002 and can be answered. But there is simply no voice.

According to the Howto (http://www.freepbx.org/support/documentation/howtos/howto-setup-a-remote-sip-extension), "if we assume in this example that your FreePBX system has an internal IP address of 192.168.1.100, that you didn’t change the default 5060 port, and that you changed the lower range of the RTP Media Port from 10000 to 10001, then you will want:
UDP/5060 -> Forward to 192.168.1.100
UDP/10000-20000 -> Forward to 192.168.1.100 "

Why is the lower range of the RTP Media Port changed to 10001 but the port forwarding is from 10000?

My rtp.conf contains:
rtpstart=10000
rtpend=10999

I think my firewall port forwarding is done correctly as 5091 works.

My Sipura PSTN Line is not registered. I don’t know whether internal ext 3003 can dial through the PSTN and get voice as there is no one at the location right now. But I have a duplicate set-up side-by-side (except no remote extension) and that one confirms that voice is not an issue from internal extensions even if the Sipura PSTN Line is not registered.

What could be the cause of the missing voice? Thanks.

Sorry, the diagram got messed up.

Basically the PBX has three connections now: a trunk to a Sipura PSTN Line, extension 3003 to the Sipura Line 1, and extension 3002 remote.

Firewall should be below || but it seems multiple spaces are ignored.