---
title: "3CX rInstance Configuration"
slug: "3cx-rinstance-configuration"
updated: 2025-01-28T17:27:39Z
published: 2025-01-28T17:27:39Z
canonical: "support.bcmone.com/3cx-rinstance-configuration"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://support.bcmone.com/llms.txt
> Use this file to discover all available pages before exploring further.

# 3CX rInstance Configuration

3CX now expects all providers to include the [“rInstance” parameter](https://www.3cx.com/docs/supported-sip-trunk-requirements/) in SIP messages. This directly impacts how Flowroute handles [inbound calls](https://www.3cx.com/docs/sip-trunk-inbound-calls/) and [SIP registrations](https://www.3cx.com/docs/sip-trunk-registration-authentication/) with 3CX. In order to comply with the new 3CX requirements, we are implementing important changes to how interconnection for 3CX is handled.

**After March 28, 2023, only one SIP registration from 3CX will be allowed per account if you use SIP digest registration as your inbound routing strategy. Otherwise, inbound calls will fail.**

#### What's New?

When 3CX sends a REGISTER message, it also sends a “rInstance” parameter with a unique value in the “Contact” header. 3CX initially attempts to find a match against a SIP trunk. If a match exists, 3CX will then check if this “rInstance” value was used to register one of the configured SIP trunks. If found, 3CX matches it with that specific SIP trunk. This hard-coded function cannot be disabled.

#### **Who is Impacted?**

If your Flowroute account Tech Prefix/SIP trunk has more than 1 active [SIP registration from 3CX](https://manage.flowroute.com/accounts/interconnection/) and at least 1 [DID number](https://manage.flowroute.com/accounts/dids/) that is using SIP digest registration as its **primary** inbound routing strategy (doesn't apply to failover route), then you have to take action to address this change.

#### **Options Going Forward**:

1. Reconfigure default inbound routes to use [host-based routes](https://support.bcmone.com/flowroute-support/docs/host-based-routing-for-inbound-calls-to-your-dids) instead (requires static IP or host name).
2. Distribute affected DID numbers between different [(sub)accounts](https://support.bcmone.com/flowroute-support/docs/sub-account-and-multiuser-overview). Please get in touch with our Support team to get assistance during this process at support@flowroute.com.

#### **3CX Resources:**

[Inbound Calls](https://www.3cx.com/docs/sip-trunk-inbound-calls/)

[Registration / Authentication](https://www.3cx.com/docs/sip-trunk-registration-authentication/)

[Requirements for VoIP Providers](https://www.3cx.com/docs/sip-trunk-registration-authentication/)