The Wiki of Unify contains information on clients and devices, communications systems and unified communications. - Unify GmbH & Co. KG is a Trademark Licensee of Siemens AG.
DHCP = Dynamic Host Configuration Protocol
IP phones like e.g. optiPoint 410/420 S contain a Dynamic Host Configuration Protocol (DHCP) client that supports automatic configuration of various parameters. If DHCP is enabled in the phone, the phone will try to obtain the following options that are essential for the configuration of its Ethernet interface automatically from a DHCP server:
- Terminal IP Address
- Terminal Mask (Network Mask)
If the phone fails to configure its Ethernet interface from a DHCP server it will eventually time-out indicating no DHCP server found and imminent restart.
Parameters that are not essential to basic network configuration the operation can be obtained by DHCP optionally and - if not returned - will not cause a reboot.
- Default Route (Routers option 3)
- IP Routing/Route 1 & 2 (Static Routes option 33)
- SNTP IP Address (NTP Server option 42)
- Timezone offset (Time Server Offset option 2)
- Primary/Secondary DNS IP Addresses (DNS Server option 6)
- DNS Domain Name (DNS Domain option 15)
- SIP Addresses / SIP Server & Registrar (SIP Server option 120)
- Vendor Unique (option 43 for VLAN information and configuration server/deployment service) - see VLAN ID Discovery over DHCP
When requesting its IP address, a telephone may also send (apart from other information) its default host name to the DHCP server. Please refer to the datasheet for details.