Hello all,
i am currently working on integration of asterisk and openser with the following call flow

UAC1,UAC2            Single WAN connection                    OPENSER              ASTERISK
|                                                        |
| --------------REGISTER-2 ------>|----------REGISTER-2 ----------->|                                |
|<-------------------200-2---------------|<------------200-2----------------------|                                |
|                                            |                                            |                                |
|-----------------INVITE-1----------->|---------------INVITE-1------------->|                                 |
|<--------------------407-1------------- |<----------------407-1------------------|                                |
|--------------------ACK-1------------>|-----------------ACK-1--------------->|                                |
|                                            |                                            |                                |
|-----------------INVITE-2----------->|------------INVITE-2---------------->|-------INVITE-2---------->|
|<------------INVITE-102------------|<------------INVITE-102-------------|<-----INVITE-102---------|
|                                           |                                             |                                 |
|                                           |                                             |                                 |
|---------------180-102--------------->|---------------180-102--------------->|-------180-102------------->|
|<-----------------180-2----------------|-----------------180-2-------------------|<------180-2------------------|
|                                           |                                             |                                 |
|                                           |                                             |                                 |
|---------------200-102--------------->|---------------200-102---------------->|-------200-102------------->|
|<-----------------200-2----------------|-----------------200-2--------------------|<----200-2--------------------|
|                                           |                                             |                                  |
|                                           |                                             |                                  |
|--------------ACK-2----------------->|---------------ACK-2------------------->|--------ACK-2-------------->|
|<-----------------ACK-102-----------|-----------------ACK-102---------------|<-----ACK-102--------------|


1)users REGISTERED at openser
2)INVITE goes through openser to asterisk and back again to openser
  then from openser to the respective user agent
3)actually there are 2 call-leg situation at asterisk( no: 2 and no:102)
4)both openser and asterisk running behind single WAN connection and both are
running with private IPs and in the gateway router inbound packets are forwarded
to openser

is it feasible architecture as i described above because i want to put
total setup behind NAT

suggestions required


Thanks in advance
Srinivas Antarvedi