There is an office that current has 6 - 8 line avaya phones, they are currently connected to a standard avaya PBX system. And use 8 land lines
Is there a way to connect them to an Asterisk system, so that they will be able to make calls using one standard SIP/DID line account. Will it still be possible to use the asterisk IVR and voice mail? And also have that you can transfer from one extension to another?