Set Provisioning-Server-URL via DHCP option 114

The DHCP option 114 which can be used to configure the URL of the provisioning server in Gigaset IP phones is <114> and implemented as following:

URL Option
This option is used to configure the provisioning server URL. URLs are specified in RFC 1738. 
The code for this option is 114, and its maximum length is 74 characters -->

  Code  Len    URL
  +------+---+----+----+----+---
   | 114 | n | c1 | c2 | c3 | ...
  +------+---+----+----+----+---

Example
Here an example configuration of a Linux DHCP-Server:

  dhcpd.conf
  snip>>
  option dhcp_114_FW_URL code 114 = text;

  option dhcp_114_FW_URL  "profile.gigaset.net/device";

  # or for example
  # option dhcp_114_FW_URL  "192.168.1.59:88/chagall/";
  <<snip

How to change DHCP option 114 in a draytek router.