Integrations / Business phone systems and carriers

Use AssistCall with Nextiva

Keep your Nextiva number. Forward it to AssistCall when you're busy, don't pick up or after hours, and every call gets answered, booked or turned into a message, with a summary by email.

Nextiva: Cloud phone system and customer communications platform (NextivaONE) for small and mid-size businesses.

Connects

Example call

A caller asks an insurance agency for a quote while both agents are on calls. After the set rings, Call Forward When Unanswered sends the call to AssistCall, which takes the details, and a Zap adds the caller as a Nextiva contact.

• Turn on Call Forward When Unanswered to your AssistCall number so calls nobody picks up after a few rings are answered instead of going to voicemail.
• Set Call Forward Not Reachable to AssistCall so calls are still answered if your office loses power or internet and the phones go offline.
• When AssistCall captures a new lead, a Zap uses Nextiva's Create Contact action so the caller's name shows up the next time they call.

How it connects

• Call forwarding: Forward your business line to AssistCall when busy, after hours or always. Works with any carrier.
• Zapier: Send AssistCall events to a Zap (Webhooks by Zapier, Catch Hook), then use the app's Zapier actions. Needs a paid Zapier plan.

About Nextiva's API

• API access not confirmed
• Style: SDKs published; server-side REST API access not self-serve as far as we found
• Authentication: Not published
• On Zapier: yes. On Make: no.

Nextiva's developer portal offers front-end SDKs, but a third-party review found server-side REST and webhook access goes through Nextiva sales, with authentication methods unpublished, so AssistCall doesn't call Nextiva's API live. Zapier's Nextiva app has New Missed Call, New Received Call, New Voicemail and New Contact triggers and a Create Contact action; no Make app was found. Forwarding options: Always, Busy, Unanswered (after a set number of rings), Not Reachable and Selective (rule-based), set per user in the Voice Portal (Users > Manage Users > user > Forwarding). User forwarding applies to direct calls only, not calls distributed by a call center or call group, and Selective rules take priority over Not Reachable.

Not included: no one-click Nextiva app, no listing in Nextiva's marketplace, no two-way sync, and no partnership with Nextiva.

Researched by the AssistCall team and checked against Nextiva's public pages on October 24, 2026. Nextiva is a trademark of Nextiva. AssistCall is an independent product of Starling Global LLC and is not affiliated with, endorsed by, sponsored by or approved by Nextiva.

More Business phone systems and carriers integrations

• AT&T Business: AT&T's business wireless, fiber and phone service, which many small businesses use for the mobile or landline number printed on their trucks, cards and listings.
• Comcast Business: Comcast's internet and business phone service (Business Voice and VoiceEdge) for offices, shops and restaurants in its cable footprint.
• RingCentral: Cloud business phone system (RingEX) with calling, texting, video and team chat in one app, used by small offices up to large companies.
• Spectrum Business: Charter's internet, mobile and business phone service (Spectrum Business Voice) for small businesses in Spectrum service areas.
• T-Mobile for Business: T-Mobile's wireless and internet service for small businesses, often the owner's mobile number doubling as the business line.
• Verizon Business: Verizon's business wireless, internet and phone service, used by many small businesses whose main number is an owner's or staff member's Verizon mobile line.

All product and company names in this directory are trademarks or registered trademarks of their respective owners, used only to identify systems AssistCall can send call information to or receive information from. Their use does not imply any affiliation with or endorsement by their owners. AssistCall connects using signed webhooks, the business's own API keys, automation platforms (Zapier, Make, n8n) the business sets up in its own account, and call forwarding. AssistCall does not provide one-click connectors, marketplace apps, certifications or two-way record or calendar sync, and does not sign HIPAA business associate agreements. Vendor features, plans and API access can change; information last checked October 24, 2026.