Help me with the dial plan

Hello, I have my asterisk pbx working perfectly exept that when some client call to my bussiness, the IVR System start correctly, and if i call to my bussiness again using my cellphone, the line sound busy :S

How i make something like my asterisk box support 2 online at the same times calls without busy ring, using queues? Hanggroups/?? Please post here some lines HOw to do it
Thanks, i hope yours helps.

You ask your telephony supplier to supply you with a trunk with a capacity of at least two erlangs. If you are using Dahdi or Zaptel, you will need to configure that to match what is supplied. If you are using FXO type lines, you will need to two physical lines and and two FXO ports.

A lot more information about your configuration would help.