Cisco SMB Switch troubleshooting and configuration

There’s a stack of 6 Cisco SMB 300 series switches. Out of the 6 switches, one of the switches has been configured as a main (core) switch where all the critical components like ASA Firewall, telephone system, server are connected. There are 3 VLANS created, i.e; VLAN 10 for Data, VLAN 20 for Voice and VLAN 30 for Management. We have an IP based telephone system from Cisco which is configured in the VLAN 20. Problem: The phone is getting connected across over to the Voice VLAN but the phone’s Data VLAN is not responding and am not able to ping to the GUI interface of the phone. (Cisco Small Business). Need the phone’s data and Voice VLAN’s to work in order for the phone’s to register to the telephone system.