[OpenSIPS-Users] help on failover routing

[johan]

my systen will be used for aid in this corona crisis (remote diagnosis 
by doctors).

We use a softphone on a mobile phone, this softphone has a DID assigned 
to itself.

The mobile phone has a real mobile number also.

The idea is when a call comes in from the provider on the DID assigned 
to that user, we call the softphone via data connection. If that doesn't 
work, the user should be contacted on his real outbound number


so:

provider receives call on DID that belongs to the user -> provider sends 
call to our system -> we dial the softphone of the user who has that 
DID-> if that call fails or cannot be made, we send the call back to the 
provider as an INVITE to his real mobile number.


Hence,

- when the softphone is registered, a call comes on that DID in udp (we 
do lookup_location) and we send it to the user in tls (this works)

- when the softphone is off for a long time, there is no record in 
location so then I route the call via the provider to his real mobile 
number (this works also)

- the problem is when the mobile looses his dataconnection, then I do 
have a record in location, I try to send the call, which will fail.   
Upon failure, I drop the record in subscriber. And here the problem begins.

The invite is adapted at this point already for tls => provider doesn't 
want it as he is udp.


So how can I have the original request back for routing to the real 
mobile number ? Or how can I check if the user is still connected (aka 
how can I send options to see if he's alive) before calling t_relay.