CISCO: How to add a media server from SDP to the Internet?

Question

Telephony

I am armed with CISCO891-K9 V01

Here is a tunnel for voip:

interface Tunnel0
ip address *REAL.IP* 255.255.255.252
ip mtu 1420
tunnel source FastEthernet8
tunnel mode ipsec ipv4
tunnel destination *REAL.IP*
tunnel protection ipsec profile voip
!
!

The provider gives a static IP, Internet access is configured like this:
interface FastEthernet8
description <<< Outside >>>
ip address *MY.IP* 255.255.255.0
ip nat outside
ip virtual-reassembly
duplex auto
speed auto
!
!

ip nat inside source list 1 interface FastEthernet8 overload
ip nat inside source list NAT_outside interface FastEthernet8 overload
ip route 0.0.0.0 0.0.0.0 *ISP_GATEWAY*
!
ip access-list extended NAT_outside
deny ip 192.168.0.0 0.0.0.255 10.0.0.0 0.0.0.255
permit ip 192.168.0.0 0.0.0.255 any
!
access-list 1 permit 192.168.0.0 0.0.0.255

That's the question, the Internet works fine at a speed of 100mb / s,
but the telephony is buggy, it doesn't ring, then it hangs up ..
I was told that I need to add a MEDIA SERVER from SDP.
How to do it and what is it?

Answer 1

>> MEDIA SERVER do the same via SDP.
What to do? Do you have a media server separate from the telephony server? Where is the telephony server, version? Where are the telephones located? Why the tunnel at all?