The issue i have here is our cisco router (2821) can only utilise 3 out of the 6 lines we have with Telstra (Telecom provider). We have 3 x ISDN 2s and should be getting 6 in/out lines concurrently however it seems like everytime we got 3 people on the line the phones reach a max and will not call out.
Can anyone give me a series of testing commands and what i should look out for?
I've tried sh isdn status and all looks good. Also it should as all the 3 interfaces lights up but they are only using one of the 2 lines available.