In order to display an asset page instead of only a MAC address connected to a switch, the assets must have been scanned. If that is the case, Lansweeper creates a link to the connected asset's asset page. Pre-requisites for scanning of network devices can be found
here (not only SNMP is being used, but other protocols as well, i.e. SIP). Perform a test with
Program Files (x86)\Lansweeper\Actions\devicetester.exe to the IP address of one of the phones which are not being displayed. If the test is successful and some data is being returned, review your setup under
Configuration\Scanning methods, section
IP Address Range scanning in order to ensure that these phones are being scanned by Lansweeper.