generated: '2026-07-17'
method: searched
source: https://docs.agentphone.ai/documentation/reference/messaging-rate-limits
signal:
  status_code: 429
  retry_after_header: Retry-After
  error_code: RATE_LIMIT_EXCEEDED
  behavior: >-
    API request throttling returns 429 with a Retry-After header. Messaging
    over carrier caps is NOT dropped — AgentPhone enqueues and delivers as
    throughput frees up.
api_limits:
- scope: register (A2P registration)
  limit_count: 5
  window_seconds: 3600
  note: 'Observed in RATE_LIMIT_EXCEEDED example (Limit: 5 requests per 3600s).'
sms_10dlc_daily_segments:
- {campaign_type: Sole proprietor, tmobile_daily: 1000, estimated_total: 3000}
- {campaign_type: Low volume, tmobile_daily: 2000, estimated_total: 6000}
- {campaign_type: High volume - low trust, tmobile_daily: 2000, estimated_total: 6000}
- {campaign_type: High volume - standard, tmobile_daily: 10000, estimated_total: 30000}
- {campaign_type: High volume - high trust, tmobile_daily: 40000, estimated_total: 120000}
- {campaign_type: High volume - highest trust, tmobile_daily: 200000, estimated_total: 600000}
sms_throughput_mps:
- {campaign_type: Sole proprietor, mps: 2.25}
- {campaign_type: Low volume, mps: 3.75}
- {campaign_type: High volume - standard, mps: 12}
- {campaign_type: High volume - high trust, mps: 120}
- {campaign_type: High volume - highest trust, mps: 225}
imessage_limits:
- {scenario: Inbound (contact texts you first), limit_count: 1000, unit: contacts/day/line}
- {scenario: Reply within 24h of last inbound, limit: unlimited}
- {scenario: Outbound-first (cold outreach), limit_count: 50, unit: contacts/day/line}
notes: >-
  A segment is 160 chars (70 for Unicode). SMS caps are carrier-set (10DLC
  campaign type + vetting/trust score), not AgentPhone-set. Limits are
  per-line; load-balance across numbers for higher capacity.