Connect a Fanvil desk phone to a NumberGroup SIP trunk
Map your NumberGroup SIP trunk credentials to the right fields on a Fanvil X-series IP phone. Field-by-field mapping table plus a link to Fanvil's own model manual for the exact navigation.
This registers a Fanvil X-series IP desk phone directly to a NumberGroup SIP trunk — no PBX in between. The mapping applies across the X-series; the exact label wording shifts a little between the 3/4-line models and the X/XU/V firmware lines, so the table links to Fanvil's own manual for your model.
When you ask us to set the trunk up, request Send Numbers As set to "United Kingdom" so Caller ID lands in the familiar 01214001262 format.
The credentials and settings your device needs to register against the NumberGroup SIP trunk are:
- Domain / registrar:
sip.numbergroup.com - Authorisation ID (also called SIP username): looks like
T-AAAAAA-NNNe.g.T-102377-001 - Password: a random string we generate per trunk
- User-Agent Type: we set this our side to match your device (e.g. 3CX Phonesystem, DDI in R-URI (Asterisk), RFC3261 Standard Trunk) so DDIs present in the format your equipment expects
- Send Numbers As: also set our side — pick the format that works best for your platform:
- International (+xx) — true E.164 (
+441214001262) for 3CX, Cisco, Yealink and most modern PBXs - International (xx) — bare digits (
441214001262) for Asterisk / FreeSWITCH dialplan regex - United Kingdom — UK format (
01214001262) for direct-register desk phones / softphones where humans read the Caller ID
- International (+xx) — true E.164 (
- Allowed IPs (optional): for an extra security layer we can lock the trunk to only register from your office IPs — tell us which when you ask
Once you have the credentials, the rest of this guide walks through the device-side config. If you'd rather skip the config altogether, ask us — we'll do it for you on most common PBXs and phones.
Field mapping
Fanvil owns the click-path and keeps it current — the table below is the part that's specific to your NumberGroup trunk.
Find the phone's IP on the handset (menu/OK key → Status), browse to it from a computer on the same LAN, then go to Line → SIP, select a line, and work through Basic Settings, Advanced Settings and Codecs Settings.
Full navigation is in the manufacturer's own guide: Fanvil Knowledge Base (kb.fanvil.com) — find your model's manual. We keep the click-path with them so it stays current — the table below is the part that's specific to your NumberGroup trunk.
| NumberGroup value | Fanvil X-series field |
|---|---|
| sip.numbergroup.com | Server Name / SIP Proxy Server Address (Basic Settings) |
| 5060 | Server Port (Basic Settings) |
| UDP | Transport Protocol (Basic Settings) |
| T-AAAAAA-NNN | Username (Basic Settings) |
| T-AAAAAA-NNN | Authentication Name (Basic Settings) |
| your trunk password | Authentication Password (Basic Settings) |
| RFC2833 | DTMF mode (Advanced Settings) |
| STUN off, rport on | NAT settings (Advanced Settings) |
| PCMU, PCMA, G722, G729 | codec order (Codecs Settings) |
Split-field note: Fanvil separates Username (the SIP user) from Authentication Name (the auth ID). On a NumberGroup trunk both take the same value — your T-AAAAAA-NNN.
Verify
- The screen shows the line registered (green) within a few seconds
- We can confirm the trunk has registered our side — ring us or check the trunk-live email
- Dial your mobile to confirm Caller ID; ring your DDI from a mobile to confirm inbound
If it won't register
- Wrong Username / Authentication Password — re-check against the trunk email
- Server address must be
sip.numbergroup.comexactly - Outbound UDP 5060 blocked on your network firewall
- One-way audio: confirm rport is enabled, disable SIP ALG on the router, confirm STUN is disabled
- Outbound rejected with 403: your Default CLI on the trunk isn't one of your DDIs — fix on the trunk
Set fraud caps before going live
A single desk phone should never place more than 1–2 simultaneous calls. Ask us to set Fraud Detection Simultaneous Calls to 2 and a sensible Daily Spend ceiling. See our telecom fraud guide.
Phones at supplier cost
Members get Grandstream desk phones at our distributor price (£28 – £83 ex-VAT), and we'll provision a Fanvil, Yealink or Snom you already own at no extra charge.