String vs vtxMobile
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
String
Enhance customer engagement with a business SMS and voice platform. Organize your inbox, automate responses, and manage contacts efficiently. Send personalized messages to individuals or groups, and access your workflow from any device.
- Use existing or new phone numbers
- Organize inbox with sales funnel view
- Automated responses and auto-replies
- Contact management and CRM integrations
- 1-1, group, and mass messaging
- Templates and voicemail transcription
- Browser and mobile app access
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Boost your brand engagement with String’s intuitive business SMS marketing, text and voice. ANY PHONE NUMBER, EVEN LANDLINES Use your existing mobile or landline number with String. Select a new local number or upgrade to a vanity or toll free number of your choice. ORGANIZE YOUR INBOX Transform your inbox into a sales funnel or kanban board with various viewing, filtering and tagging options — Stay on top of your conversations and never miss a message again. POWERFUL MESSAGE MANAGEMENT Mark Unread and Archive — You love it for your emails, you’ll love it for your texts. STAY RESPONSIVE, 24/7 Amplify your interaction with automations and Auto-Replies — Respond to texts and missed calls on time, every time. TAP INTO ENDLESS POSSIBILITIES Contact Management & Integrations — Save important contact notes directly from the message thread. Capture contacts, import from your phone or computer,, automate workflows, integrate with tools you love (like your CRM, etc). REACH THE MASSES, OR JUST ONE Conversational, Groups or Mass Messaging — Respond directly with 1-1 messaging, message with a group,r or send personalized Mass Messages to multiple people at once, individually. BUILD A LOYAL CUSTOMER BASE Send promos, reminders and confirmations and never miss a lead, client or customer with Elite features like triggered Keyword Responses, and Auto-Replies. SAVE TIME Templates — No more copy-pasting the same message over and over. No time to listen to voicemail? View voicemail transcriptions in your inbox with visual voicemail. USE IT ANYWHERE Browser & Mobile Apps — Increase your workflow efficiency with access to String from your computer and mobile device. CALL FORWARDING & VOICE Separate your personal and professional calls with call forwarding and flexible voice settings. GOT QUESTIONS? Email our stellar support at support@joinstring.com. Find helpful articles, join our customer community and create tickets in our Help Center: https://help.joinstring.com/hc/en-us Terms of Service: https://www.joinstring.com/terms Privacy Policy: https://www.joinstring.com/privacy
vtxMobile
This app transforms your mobile device into a business phone extension, enabling free inter-office calls and cost-effective international communication. It offers features like voicemail, call transfer, and team messaging for seamless on-the-go business operations.
- Free inter-office extension calls
- Company caller ID
- Cost-effective international calls
- Three-way calling
- Call transfer
- Voicemail
- Team messaging
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Exclusively for all VTX IP PBX customers: Wi-Fi or data plan required. vtxMobile is part of our unified communications solution that turns your device into a business line or office phone extension on the go! - Dial and answer inter-office extension calls from worldwide for free - Make calls showing your company caller ID. - Make cheap calls from anywhere to anywhere in the world with your existing VTX service plan - Three-way calling - Transfer calls to another extension (worldwide) or another phone number - Voicemail - Call history, call waiting, transfer calls to another extension or phone number - Automatically populates interoffice directory as co-worker contacts - Integrates with your device’s contact list, for easy dialing. It allows you to make cheap international calls wherever you are, without using your wireless airtime or roaming charges. - International Coverage: Save 90% on international roaming calls, when you’re traveling outside the U.S. and Canada with free Wi-Fi access. - Team messaging and collaboration - Answering rules management Legal Notes - vtxMobile works best on WiFi. Spotty signals of data network may hinder voice quality. - Use of vtxMobile with mobile data network may result data charges from your wireless provider. - vtxMobile is not responsible for the cost of international calls made from the iPhone or iPad dialer or other applications. Therefore, if you did not use the VTX keypad to dial the international calls, then you know that the VTX VoIP app is not being used, and the call will be handled by your mobile operator at your expense.
Screenshots
Verdict
The clearest difference is rating: vtxMobile at 5.0 against String's 3.5. vtxMobile also leads on monetization model (free vs free with in-app purchases). String's advantage is ratings volume (62 vs 1) and iOS requirement (15.0 vs 17.0). On price, update cadence, ads and in-app purchases there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
vtxMobile holds the better App Store score, 5.0 against 3.5. That said, the two scores are not equally well evidenced: String has 62 ratings behind it against 1, so its average is the more settled of the two.
Both ship on a similar rhythm, roughly every 2 months. The most recent releases landed on October 21, 2026 and October 6, 2026 respectively.
| Parameter | String | vtxMobile |
|---|---|---|
| Price | Free | Free |
| Rating | 3.5 (62 ratings) | 5.0 (1 ratings) — better |
| Positive reviews | 68.6% of reviews | — |
| Number of ratings | 62 — better | 1 |
| Update frequency | Every 2 months | Every 2 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free with in-app purchases | Free — better |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 15.0 — better | 17.0 |
| Further details — not scored | ||
| Size | 68 MB | 124 MB |
| Age rating | 4+ | 4+ |
| Developer | NumberBarn, LLC | Kloud Communications Inc. |
Customer experience
String
vtxMobile
In-app purchases
String
No in-app purchases
vtxMobile
No in-app purchases









