Transfered Calls not Dropping

Hi
I am running a campaign with call transfering.
Basically when the agent gets a sale they park the customer. click tannsfer/conf
Dial an outside number with customer. They then talk to the number they dia for the lawyers, then unpark the customer introduce the customer to the lawyers and then click leave 3 way call and leave the customer and lawyer talking.
this all works fine, however the line between the customer takes a while to drop even after the customer and lawyer have hung up and it ties up the phone line for both.
any suggestions on this?
Regards
I am running a campaign with call transfering.
Basically when the agent gets a sale they park the customer. click tannsfer/conf
Dial an outside number with customer. They then talk to the number they dia for the lawyers, then unpark the customer introduce the customer to the lawyers and then click leave 3 way call and leave the customer and lawyer talking.
this all works fine, however the line between the customer takes a while to drop even after the customer and lawyer have hung up and it ties up the phone line for both.
any suggestions on this?
Regards