LinuxQuestions.org - asterisk realm authentification

hi
I just installed asteriks on my remote server ,and set up 2 account for test purpose.
i added these lines to sip.conf

Code:

[benchabane]

type=friend

username=benchabane

secret=tcpip13

host=dynamic

context=mygroup



[ilvista]

type=friend

username=ilvista

secret=tcpip13

host=dynamic

context=mygroup

and these to extensions.conf

Code:



[mygroup]

exten =>1234,1,Dial(SIP/ilvista)

exten =>4321,1,Dial(SIP/benchabane)

at first things worked fine ,but now it's not and i don't know why?
every time i try to call the other user twinkle keep asking user and password for realm:"asterisk"

Code:

login required for realm:"asterisk"

and when i enter the user login and password then nothing happens.

here is what asteriks gives me

Code:

Jan 26 15:35:17] WARNING[1792]: app_dial.c:1242 dial_exec_full: Unable to create channel of type 'SIP' (cause 20 - Unknown)

  == Everyone is busy/congested at this time (1:0/0/1)

  == Auto fallthrough, channel 'SIP/benchabane-e4003d30' status is 'CHANUNAVAIL'

[Jan 26 15:35:17] NOTICE[5474]: chan_sip.c:14615 handle_request_invite: Unable to create/find SIP channel for this INVITE

thx in advance.