The tenant will be required a phone for the Intercom-Phone system. The options will include a landline phone which will plug into an RJ11 jack within the unit. This will be the simplest way, but likely the least flexible. The second option will be to use a SIP client on a smartphone. This will allow the tenant to answer the door even while out (using data). The third option will be to forward the connection to a regular telephone number. If the tenant should have to change their number, they will need to notify the office.