How the Vocera SIP Telephony Gateway Handles Paging Dial Strings

The Vocera SIP Telephony Gateway handles paging by explicitly setting timers for dial strings, and pause characters are used to control when DTMF is sent to the PBX.

The following figure shows the format of a valid paging dial string for Vocera SIP Telephony Gateway:

Figure 1. Paging dial string
  1. Primary Dial String – a dialable phone number.

  2. Comma – separates the primary dial string from the primary extension. This separating comma along with any commas in the primary extension will be added to the DTMF queue as pauses. The comma also distinguishes the primary dial string from the primary extension. The duration of a comma pause is configurable for each trunk access code; see Configuring Trunk Access Codes (TACs).

  3. Primary Extension – a string of DTMF digits to be sent to the PBX. It must start with at least one comma, and it cannot contain a semicolon.

  4. Semicolon – a single semicolon for the Connect Pause. The semicolon introduces the delay before sending the secondary dial string. It also disginguishes between the primary dial string/extension and the secondary dial string. The duration of a semicolon pause is configurable for each trunk access code; see Configuring Trunk Access Codes (TACs).

  5. Secondary Dial String – a string of DTMF digits to be sent to the PBX. It must start with a semicolon. After that, any valid DTMF character or pause character (comma or semicolon) is valid.

Vocera SIP Telephony Gateway can accept a dial string of the form:

4085551234,,9898,,##;5559999,,,3232,,,5,,7,,555667777;;##*

Vocera SIP Telephony Gateway interprets this dial string as follows:

The comma and semicolon serve two distinct functions in the dial string. They introduce pauses in sending DTMF, and they affect the state behavior of the call by demarking the primary dialed number, the primary extension, and the secondary dial string.