VoIP: Voice over Internet Protocol: calls travelling as data instead of cellular voice. The transport underneath cloud telephony, with its costs and its answer-rate consequences in mobile-first markets.
Definitions checked 2 September 2026.
VoIP, voice over internet protocol, is the technology that carries a phone call as data packets over the internet instead of as a cellular or landline voice circuit. WhatsApp voice calls, Zoom, and every cloud telephony platform use it. For business calling it is the transport underneath virtual numbers: the app or the browser captures the voice, sends it to the provider's server, and the provider places the call onto the public phone network from a number it owns.
Its strengths are the cloud's strengths: calls from anywhere with a data connection, easy recording because the server hears everything, many agents on one number, and per-minute pricing that can be cheap for long-distance and international calling. Its weaknesses in a mobile-first market are the same list read the other way: call quality follows the data connection, which in a basement or on a highway is not there; every minute is billed; and the number the customer sees is a virtual one, which Indian caller-ID apps increasingly screen, so the same list connects less often than from a SIM.
For a small team calling its own customers in India, SIM calling wins on answer rate and cost, and VoIP wins where recording, routing or international calling is the requirement. RMDialer, which we make, places calls on the cellular network from the caller's SIM and uses the internet only to sync records. The linked post lays out SIM versus VoIP for a CRM with the numbers that matter.
What is the difference between VoIP and a SIM call?
A VoIP call travels as data over the internet from a virtual number; a SIM call travels on the mobile network from the phone's own number. SIM calls work without data and are answered more in India; VoIP calls can be recorded and routed easily.
Is VoIP cheaper for business calls?
Per minute it can be, especially internationally. For domestic outbound selling on plans with unlimited calling, a SIM call costs nothing extra, so VoIP's per-minute billing is usually the more expensive option once every seat and minute is counted.
What is the difference between a power dialer and a predictive dialer?
A power dialer calls one number at a time for one agent and waits for that call to end, so every answered call has a person ready. A predictive dialer calls several numbers at once and connects the ones that answer to whichever agent is free, which needs a call-centre server and causes dropped "silent" calls. Mobile auto dialers like RMDialer are power dialers on a SIM.
What is a SIM-based dialer and how is it different from cloud telephony?
A SIM-based dialer places calls from the SIM in the user's own phone, so the customer sees a normal mobile number and the call costs whatever the operator plan charges. Cloud telephony routes calls through a virtual number on a server and bills per user plus per minute, in return for features like IVR and recording. For outbound sales on mobile numbers, SIM calling gets answered more often and costs far less.
Do I need a virtual number to run a calling team?
No. A virtual number is only needed when calls must be routed through a cloud platform, for example for an inbound IVR. An outbound sales team can run entirely on business SIMs in the reps' phones, with the app logging every call and the owner reading the reports. Customers also answer known mobile numbers more readily than unfamiliar virtual ones.
Why do customers not answer calls from virtual numbers?
Because caller ID apps and phone dialers increasingly flag pooled virtual and VoIP numbers as spam or business calls, and because the same virtual number is often used for many campaigns. A real mobile number from a local SIM looks like a person calling, which is why SIM-based dialers report higher connect rates in India.
Can I use two SIMs for business calling on one phone?
Yes. On a dual-SIM Android phone the dialer lets you choose which SIM makes each call, or set a default business SIM for all sessions. You can also decide which SIM's calls are backed up and reported, so personal calls on the other SIM stay out of the team account.
How do I stop my business number being marked as spam?
Call from a real SIM rather than a pooled virtual number, keep daily volumes reasonable, do not call DND numbers with offers, save your business name in Truecaller and similar caller ID apps, and send a WhatsApp before or after the call so the customer recognises you. Numbers get flagged by patterns of unanswered cold calls, not by calling your own enquiries.
Which is better for an Indian sales team: SIM-based CRM or cloud call centre software?
For outbound sales on mobile numbers, SIM-based: higher answer rates, no per-minute bills, works offline, runs on phones the team already has. For high-volume inbound with IVR, queues and recording, cloud call-centre software. Many businesses run both: cloud for the support line, SIM-based for the sales team.
What is an auto dialer app?
An auto dialer app calls a list of phone numbers one after another so the caller never types a number. On Android, an app like RMDialer runs the session on the phone itself using the SIM already in it: you pick a list from Excel, a Google Sheet, an API or assigned leads, press start, and the app dials each number in turn while you mark the outcome between calls.
What is a telecalling CRM?
A telecalling CRM is customer software built around phone calls: the lead list, the dialer, the call outcome and the follow-up live in one place. The mobile kind, such as RMDialer, replaces the Android phone app on each rep's handset so every call automatically becomes a record with a status, a remark and the next follow-up, and the manager sees the whole team on a web dashboard.
What is the difference between telecalling software and a CRM?
Telecalling software is built to make and track calls (dialing lists, call logs, per-caller reports). A CRM is built to hold customer records and pipeline stages. Most Indian sales teams need both at once, which is why a telecalling CRM combines them: the call itself creates and updates the customer record, so nobody types into a separate system after the call.
What is a CRM dialer?
A CRM dialer is a single app where the dialer and the customer record are the same thing: the call screen shows the lead, and ending the call updates it. It differs from a CRM with "dialer integration", which is two products joined by a sync. RMDialer is a CRM dialer for Android that runs on the user's own SIM.
What is a business dialer app?
A business dialer app replaces the default phone app on an Android phone with one made for selling: caller ID from your own leads, the last remark on screen when a customer rings, two-tap status and follow-up after each call, automatic WhatsApp, and a call log that filters by lead status. It is a personal CRM for one owner and a team system when several people use it.
Does RMDialer work on iPhone?
No. RMDialer is an Android app because iOS does not let a third-party app replace the phone dialer, read the call log or place calls automatically. It supports Android 8.0 and above. The owner's Web CRM works in any browser, including Safari on a Mac or iPhone.
Customer reviews
What businesses say about RMDialer
Real businesses, real numbers: how owners and sales teams across India and 12+ countries use RMDialer every day.
Rated 4.9 by customers 5.0 on Google Play 1K+ downloads India + 12+ countries
“Telecaller app for Android that my staff actually use. Enquiry list is assigned to each telecaller, the auto dialer calls it from their own SIM, and test ride bookings come to me live. Punjabi interface for the girls at the desk. Price is honest, everything included, no per-user surprises.”
“We needed an auto dialer app that works on our own MTN and Airtel lines, not a call centre subscription in dollars. RMDialer runs on the phones my agents already have, dials the enquiry list, and the WhatsApp follow-up goes out after every call. Works even when the network drops and syncs later.”
GOGrace OkaforManaging director · Travel agencyLagos, Nigeria
“We looked for telecalling software for a nine-person loan team and every quote came with cloud seats and per-minute bills. RMDialer telecalling software runs on the callers' own Jio SIMs: the lead list dials itself, the remark goes on the number, and I get dials, connects and talk time per caller every evening. Cost is one flat price per user.”
KIKavita IyerOperations head · Loan DSAChennai
“Earlier I was dialling 80 to 100 portal leads a day by hand from Excel. With RMDialer auto dialer app I import the sheet, press start and it calls one by one from my own Jio SIM. Between calls I mark Interested or Site visit in two taps and the follow-up rings me on time. Closed 3 flats last month from leads I would have forgotten.”
“We tried two telecalling CRM software before this and my counsellors stopped filling them within a week. RMDialer is the phone app itself, so every admission enquiry gets logged whether they like it or not. The auto WhatsApp after call sends the fee structure by itself. I see all 4 counsellors' calls on the web CRM every evening.”
PNPriya NairOwner · Coaching instituteKochi
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