Connect Avaya IP Office to a NumberGroup SIP trunk

This is the setup for adding a NumberGroup SIP trunk to Avaya IP Office (Release 11 / R12 — the most common SME Avaya footprint in the UK). It uses IP Office Manager (or Web Manager) to add a SIP Line, configure the URI, set up an outbound short code and an incoming call route. About 30 minutes the first time.

When you ask us to set up the trunk, mention you want the User-Agent Type to "RFC3261 Standard Trunk" and Send Numbers As to "International (+xx)". IP Office's SIP Line URI forms handle leading + cleanly and it gives you predictable matching on the inbound call route.

Prerequisites

• IP Office R11 or R12 (older R9.x works but the form fields differ)
• SIP Trunk Channels licence — confirm under License in IP Office Manager
• If the IP Office is behind NAT, set the public-facing IP under System → LAN1 → Network Topology

Step 1: add the SIP Line

In IP Office Manager: right-click Line → New → SIP Line.

SIP Line tab

• Line Number: next available (e.g. 17)
• ITSP Domain Name: sip.numbergroup.com
• Local Domain Name: leave blank (defaults to LAN1 IP)
• URI Type: SIP
• Send Caller ID: Diversion Header
• Association Method: By Source IP Address
• In Service: ticked
• Check OOS: ticked
• Refresh Method: Re-Invite
• Timer (seconds): 60

Transport tab

• ITSP Proxy Address: sip.numbergroup.com
• Layer 4 Protocol: UDP
• Send Port: 5060
• Listen Port: 5060
• Use Network Topology Info: LAN 1
• Calls Route via Registrar: ticked
• Separate Registrar: leave blank

SIP Credentials tab

Click Add:

• User name: T-AAAAAA-NNN (e.g. T-102377-001)
• Authentication Name: same
• Password: your trunk password from the email we send you
• Confirm Password: same
• Expiry (mins): 60
• Registration Required: ticked

SIP URI tab

Click Add:

• Local URI: Use Internal Data → references the Incoming Caller ID set against each user (you'll set this in step 3)
• Contact: Use Internal Data
• Display Name: your business name
• Registration: 0 (the credential row created above)
• Incoming Group: 17 (matches your Line Number for clarity)
• Outgoing Group: 17
• Max Sessions: match your trunk Fraud Detection ceiling

VoIP tab

• Codec Selection: Custom
• Selected codecs (top to bottom): G.711 ALAW 64K, G.711 ULAW 64K, G.722 64K, G.729(a) 8K CS-ACELP
• Fax Transport Support: T.38 (if you use fax)
• DTMF Support: RFC 2833
• Media Security: Disabled (unless trunk Voice Mode = secure encrypted voice)
• Allow Direct Media Path: ticked
• Re-invite Supported: ticked

T38 Fax tab (only if you use fax)

Leave defaults. Disable ECM if you have reliability issues with specific destinations.

Step 2: configure user Caller ID

For each user that should be able to dial out via the trunk, set their outbound CLI on the user's SIP tab:

• SIP Name: their DDI in E.164 (+441****1263)
• SIP Display Name (Alias): their full name
• Contact: same as SIP Name

Avaya then presents the user's DDI as the outbound CLI — matched against the Default CLI we configured on the trunk / allowed CLI list.

Step 3: outbound short code

Short Code → New:

UK numbers via the trunk

• Code: 9N;
• Feature: Dial
• Telephone Number: +44N (strip the 9-0, prepend +44)
• Line Group ID: 17 (matches your trunk's Outgoing Group)

A user dials 9-0121-400-1262, IP Office strips the 9 and the leading 0, prepends +44, sends +44121400 1262 out the trunk.

International

• Code: 900N;
• Feature: Dial
• Telephone Number: +N
• Line Group ID: 17

Emergency

• Code: 999
• Feature: Dial Emergency
• Telephone Number: 999
• Line Group ID: 17

Add identical entries for 112, 101 and 111.

Step 4: incoming call route

Incoming Call Route → New:

• Bearer Capability: Any Voice
• Line Group ID: 17
• Incoming Number: the DDI you own, in E.164 (+441214001262)
• Incoming CLI: leave blank to match any

On the Destinations tab:

• Destination: an extension, hunt group, or short code (e.g. 2001 for main reception, or Main if you have an Auto Attendant)
• Fallback Extension: voicemail

Add one Incoming Call Route per DDI. For a busy site, use the Account Code field to tag arrivals for reporting.

Firewall

• UDP 5060 outbound to sip.numbergroup.com
• UDP 40750–50750 outbound (IP Office's default RTP range)
• Disable SIP ALG on the WAN edge

Debugging

• SysMonitor with SIP filter — live SIP trace, the standard Avaya diagnostic tool
• From the System Status Application: Trunks → SIP Line 17 shows registration state and active sessions
• Ring us — we'll see the registration state and recent INVITE attempts our side and can tell you what's being rejected

Common failure modes

• Registration shows "Not registered" — wrong Auth Name/Password, or Use Network Topology Info isn't pointing at LAN1
• Outbound rejected with 403 — user's SIP Name isn't a valid DDI
• One-way audio — SIP ALG on the router, or Network Topology public-IP not set
• 488 Not Acceptable — codec mismatch; re-check the VoIP tab codec list

Set fraud caps

IP Office is one of the most-attacked PBXs in the UK SME space. Belt-and-braces:

• Ask us to set Simultaneous Calls and Daily Spend tight to real peak
• Block international by default — restrict via the user's outgoing call bar settings
• Change the default IP Office admin password from Administrator/Administrator if you haven't already
• See our telecom fraud guide

Source: the device navigation in this guide follows Avaya IP Office — Configuring a SIP Trunk. We keep the click-path with the manufacturer so it stays current — the NumberGroup trunk values above are the part specific to your account.