Dialer traffic comes from automatic or predictive dialers that call lists of numbers, which produces many short or unanswered calls at a high rate per second. Most premium and conversational routes refuse it, so a SIP trunk for an auto dialer needs routes that explicitly accept dialer traffic, usually with agreed limits on CPS, ASR and call duration.
Why many routes refuse dialer traffic
A dialer places several calls per agent and drops the ones that are not answered or reach voicemail. Seen from the route, that means:
- Low ASR, because many numbers do not answer or are invalid.
- Low ACD, because many answered calls are short.
- High CPS, because the dialer starts calls in bursts.
- Many calls with the same caller ID, which analytics and operators read as possible robocalls.
Operators and upstream carriers monitor these patterns. A route that carries too much of this traffic can be blocked, its CLI downgraded, or its supplier penalized. Carriers protect their routes by refusing dialer traffic or by keeping it on separate capacity. See VoIP traffic types and ASR, ACD and PDD.
What carriers that accept dialer traffic ask for
| Item | Why it is asked |
|---|---|
| Dialer type (preview, progressive, predictive) | Predictive dialers produce the most abandoned and short calls |
| CPS limit | Protects the route and the destination operator from bursts |
| Expected ASR and ACD | Some routes set a minimum ACD or penalize very short calls |
| Caller IDs used and proof of right to use them | Required for compliance in many countries |
| Campaign type and consent | Telemarketing, collections and surveys fall under different rules |
| Dedicated capacity | Keeps dialer traffic away from other customers' calls |
How to improve your chances
- Clean your lists: remove invalid and disconnected numbers before dialing. Fewer failed attempts means higher ASR and less wasted CPS. An HLR or number validation check helps on mobile numbers.
- Lower the pacing ratio: a more conservative predictive ratio means fewer abandoned calls.
- Rotate caller IDs responsibly: use numbers you own and can receive calls on, and keep them within the rules of each country. Never spoof. See CLI spoofing and robocall rules.
- Respect calling hours and do-not-call lists in each destination.
- Declare the traffic honestly: routes are cut quickly when undeclared dialer traffic shows up.
Billing on dialer routes
Because calls are short, the billing increment matters a lot. A route at 60/60 bills every 10 second call as a minute. Dialer friendly routes are often 6/6 or 1/1, sometimes at a higher per minute rate. Some carriers add a charge for very short calls or for failed attempts above a set ratio. Ask for every surcharge in writing.
US and other regulated destinations
Dialer traffic to the United States and Canada faces call authentication and robocall rules, and to the US you should expect questions about STIR/SHAKEN attestation and your caller IDs. Several other countries have registers for telemarketing callers or do-not-call lists. Check the rules of each destination before you start a campaign.
Capacity planning
Dialers need more channels per agent and more CPS than manual calling. Plan 2 to 3 channels per agent for predictive dialing and confirm the CPS limit before going live. See channels and CPS and dedicated vs shared ports.
Request a dialer route
When you request a route, state that the traffic is dialer traffic, the dialer type, your CPS and expected ACD. VoIPMatcher then sources VoIP termination only from carriers that accept it. Request a dialer route.
Frequently asked questions
Which VoIP provider works with Vicidial?
Vicidial connects to any carrier that offers a standard SIP trunk, usually with IP authentication or registration. What matters is not the brand but whether the routes behind the trunk accept predictive dialer traffic, the CPS limit, the billing increment and the caller ID rules for your destinations. Declare the dialer type when you ask for a route.
Is predictive dialing legal?
Predictive dialers are legal in many countries, but their use is regulated. Rules commonly cover consent for automated or prerecorded calls, limits on abandoned calls, calling hours and do-not-call lists. In the US the TCPA and FCC rules apply, and other countries have their own telemarketing registers. Check each destination before starting a campaign.
What is the difference between an auto dialer and a predictive dialer?
An auto dialer is any system that dials numbers automatically. A predictive dialer is a type of auto dialer that calls several numbers per agent at once, using an algorithm to predict when an agent will be free, and drops calls that are not answered. Preview and progressive dialers place one call per available agent.
How many CPS does a predictive dialer need?
It depends on the number of agents and the pacing ratio. A predictive dialer can easily send 20 or more attempts per second, most of them unanswered, while 50 agents dialing by hand rarely exceed 1 or 2 CPS. Measure attempts in your busiest minute, add a margin and agree the CPS limit before going live.
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