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Account-wide cap on call length, in seconds, applied as a hard ceiling to every inbound and outbound call on the account. The effective cap on any call is the smallest of the limits that are set — this account cap, the number's own cap, and any per-call cap — so a lower limit at another level always wins; none of them can raise the call above this account cap. Must be between 60 and 3600 seconds (1 minute to 1 hour); a value outside that range returns 400. Send null to clear it (falls back to the global default). When a cap is active, Dial automatically injects a warning to the agent ~40 seconds before the hard cut, prompting it to wrap up naturally.