Routing queries based on carrier phrase registration

A computing device comprising:

• data processing hardware;
• and
• memory hardware in communication with the data processing hardware and storing instructions that when executed by the data processing hardware cause the data processing hardware to perform operations comprising:
• receiving a voice input captured by the computing device, the voice input comprising a beginning portion and a remaining portion;
• determining that the beginning portion matches a particular carrier phrase from among a plurality of carrier phrases, each respective carrier phrase associated with a corresponding application and a corresponding pre-defined action;
• based determining that the beginning portion matches the particular carrier phrase, converting the remaining portion of the voice input into a textual representation;
• and
• instructing the corresponding application to perform the corresponding pre-defined action using the textual representation of the remaining portion of the voice input, the corresponding application and the corresponding pre-defined action each associated with the particular carrier phrase, wherein the particular carrier phrase has been registered by a third-party application program in response to a request by or on behalf of the third-party application program to reserve the particular carrier phrase.