Are they analog lines or are they SIP lines? I know Cbeyond is a Sip provider. If that is the case, then if other people are on the phone and depending on how many licenses there are for MGI they could be tied up. For example, they have 4 mgi licenses for 4 sip trunks. If 4 people are on the phone, then yes no mgi channels are available to be accessed cause they are all busy.