... /Three-way conference/Call waiting fun Important: It can store two SIP accounts, press 1# key, choose the first SIP ... the second SIP Account to call...2, the two SIP Account from two ITSP, the first SIP Account call to USA ... call...3, you need to found an network in group company, but also need to call any number, you can set ... in a semiduplex way to ensure the talking quality; Two Line VoIP Phone