This is a read-write text field, up to 128 characters, specifying a technology prefix that, together with the called-party address, is passed to an H.323 gatekeeper in an Admission Request during call setup to help resolve the destination address. An admin configures this so the gatekeeper can route calls to the correct technology or gateway type based on the prefix, rather than the destination address alone. For example, distinguishing fax gateways from voice gateways registered under the same gatekeeper might be done by assigning them different technology prefixes on their respective peers.