Connect Cisco Unified Communications Manager to a NumberGroup SIP trunk

This is the setup for adding a NumberGroup SIP trunk to Cisco Unified Communications Manager (CUCM 12.5 / 14 / 15). Cisco is the most opinionated of the PBX vendors — there are no provider templates, you build the SIP profile, security profile and trunk manually — but the steps below are the working order. Plan an hour the first time, 15 minutes thereafter.

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)". Cisco CUCM prefers true E.164 (+44…) internally — translation patterns then strip the + for outbound or add it back for inbound display.

Step 1: create the SIP profile

Device → Device Settings → SIP Profile → Add New (or copy Standard SIP Profile).

• Name: NumberGroup SIP Profile
• Default MTP Telephony Event Payload Type: 101
• Redirect by Application: unchecked
• Disable Early Media on 180: unchecked
• Outbound Call Routing → Reroute Outbound on Originating Trunk: unchecked
• SIP Rel1XX Options: Disabled
• RFC 2543 Hold: RFC 3264 Hold
• Use Fully Qualified Domain in SIP Requests: checked
• Allow Presentation Sharing using BFCP: unchecked
• Allow Multiple Codecs in Answer SDP: checked
• Send Send-Receive SDP in mid-call INVITE: checked

Step 2: SIP trunk security profile

System → Security → SIP Trunk Security Profile → Add New:

• Name: NumberGroup Trunk Security Profile
• Device Security Mode: Non Secure (or Encrypted if you've set the trunk Voice Mode to "secure encrypted voice")
• Incoming Transport Type: UDP
• Outgoing Transport Type: UDP
• Enable Digest Authentication: checked
• Nonce Validity Time: 600
• Incoming Port: 5060
• Accept Presence Subscription: unchecked
• Accept Out-of-Dialog REFER: unchecked
• Accept Unsolicited Notification: unchecked

Step 3: add the SIP trunk

Device → Trunk → Add New → SIP Trunk → Next.

• Device Name: NUMBERGROUP_TRUNK
• Description: NumberGroup SIP Trunk
• Device Pool: Default
• Location: Hub_None
• Run On All Active Unified CM Nodes: checked (if clustered)

Under Inbound Calls:

• Calling Search Space: your inbound CSS
• Significant Digits: 12 (full E.164 minus the +)
• Incoming Called Party Settings → Number Type: International

Under Outbound Calls:

• Calling Party Selection: First Redirect Number
• Calling Line ID Presentation: Default
• Caller ID DN: your main DDI in E.164 format (+441214001262)

Under SIP Information:

• Destination Address: sip.numbergroup.com
• Destination Port: 5060
• MTP Required: unchecked
• SIP Trunk Security Profile: the profile from Step 2
• SIP Profile: the profile from Step 1
• Normalization Script: None
• DTMF Signaling Method: RFC 2833

Save, then click Reset.

Step 4: digest credentials (registration)

CUCM doesn't support outbound SIP registration natively on a SIP trunk — Cisco assumes static IP peering on enterprise trunks. Two ways to handle this with NumberGroup:

Option A (recommended): set the trunk to IP-anchored on our side

Ask us at /contact or on 0800 310 1010:

• Tell us your CUCM publisher's public IP so we can lock the trunk to it (Allowed IP)
• Contact us with your CUCM's static public IP — we'll switch the trunk to IP-anchored so it doesn't require registration

This is the simplest path for a typical site CUCM deployment.

Option B: use a CUBE in front of CUCM

Deploy a Cisco Unified Border Element (CUBE) — usually a spare ISR router — between your CUCM and the public network. The CUBE registers to sip.numbergroup.com using the standard credentials CLI block, and presents a clean SIP trunk to CUCM internally. This is the textbook Cisco architecture for ITSP integration. Ring us if you want example CUBE config — we'll walk you through it.

Step 5: outbound route pattern

Call Routing → Route/Hunt → Route Pattern → Add New:

• Route Pattern: 9.@ (or whatever your outbound access digit is)
• Route Partition: your outbound partition
• Gateway/Route List: the NumberGroup trunk
• Discard Digits: PreDot (drops the 9)
• Numbering Plan: NANP (North American Numbering Plan)  or use the GB-specific plan if installed
• Calling Party Transformations → Use Calling Party's External Phone Number Mask: checked
• Called Party Transformations → Prefix Digits (Outgoing Calls): +

For a simpler approach without using 9.@:

• 9.011! → international, discard PreDot, prefix +
• 9.0[1-9]XXXXXXXXX → UK numbers, discard 9.0, prefix +44

Step 6: inbound translation patterns

Calls land with the DDI in E.164 (+441214001262). You probably want CUCM to route by the local 4-digit extension associated with each DDI:

Call Routing → Translation Pattern → Add New:

• Translation Pattern: +441214001262
• Partition: your inbound partition
• Calling Search Space: matches your internal extension partitions
• Called Party Transformation Mask: 4001 (your local extension)

Repeat per DDI. Or for a single main number rolling to a hunt pilot, set the mask to the pilot.

Firewall

• UDP 5060 outbound to sip.numbergroup.com
• UDP 16384–32767 outbound (CUCM's default RTP range)
• Disable SIP ALG on the WAN edge

Debugging

From CUCM's CLI:

• show trace — current trace levels
• file get activelog tomcat/logs/ccmtrace/* — pull CCM traces
• Real Time Monitoring Tool (RTMT) — live SIP trace with full SIP messages, filter by your trunk name

Ring us — we can see the trunk's registration state and recent INVITE attempts — if CUCM is trying and we're rejecting, ring us and we'll tell you why.

Set fraud caps

Ask us to set Fraud Detection Simultaneous Calls and Daily Spend 50–100% above your real peak. See our telecom fraud guide for rationale.

Source: the device navigation in this guide follows Cisco Unified Communications Manager — Configure Trunks. We keep the click-path with the manufacturer so it stays current — the NumberGroup trunk values above are the part specific to your account.