Hi . is there is any way to limit the outbound calls for some users with limited amount of minutes ?
like ext 101,102 can call any outbound number for 10 mins only and they it will auto disconnect the call
Asterisk can do this with “Dial option L” - haven’t done it myself but it would be set in a Trunk configuration under “Asterisk Trunk Dial Options”. That’s all I know - Google should get you there. 
What trunk do you use to dial out, sip or dahdi?
i am using sip as my trunk
Create a new custom trunk, override asterisk trunk dial options and put inside there what was visible before plus the following
L(600000)
also in the Custom dial put the following
SIP/yoursiptrunkname/$OUTNUM$
Save the new trunk.
You make a new outbound rule with the same settings that your current has but in the cid field next to each dial pattern you will put the following
10[12]
this will let only extension 101 and 102 to use the rule. Put between the brackets every number that you want to be able to dial out through this rule.
In the trunk sequence choose the trunk that you created later.
Finally in the outbound rule order put the new rule over the rest that you have.
Thanks but what exactly this rule will do ?
i already can deny or allow any ext to use outside lines . but that is a fixed configuration .
daily i need some limited extension to use outside lines . so in old telephone system i just had to call operator and ask him for temporary give permission to my ext . so the operator will transfer a free line for me without him calling any numbers for me then i can use that line to call any outside number and once i finish the call , i will not be able to call any number outside till i call the operator again and ask him again to give me free line .