You are opening a second office. Your to-do list has 200 items. The phone system is item 187. It should be item 5.
I have helped 60 UK businesses expand from one office to two. The phone system decision made in week 1 either saves months of hassle or creates years of problems. Here is the checklist.
The Decision: Extend or Replace?
| Your Current System | Recommendation | Why |
|---|---|---|
| Cloud VoIP | Extend | Add users in admin portal, ship phones, done |
| On-premise PBX (< 3 years old) | Replace now | Cheaper than buying second PBX + connecting them |
| On-premise PBX (> 3 years old) | Replace now | Maintenance costs + second PBX = 3x cloud cost |
| BT landlines | Replace now | Cannot extend landlines to new site |
If you are on cloud VoIP already, adding a second office takes 30 minutes of admin portal configuration. If you are on anything else, now is the time to switch — before you are managing two legacy systems instead of one.
The Second Office Phone Checklist
Week 1: Numbers and Routing
- [ ] Get a local number for the new office (different area code = local presence)
- [ ] Decide: does the new office share the main number or have its own?
- [ ] Configure ring groups for the new office team
- [ ] Set up overflow: if new office is busy, overflow to main office
- [ ] Configure internal extension range (e.g., 2000-2099 for office 2)
Week 2: Network
- [ ] Verify broadband at new office: minimum 10 Mbps upload for 10 users
- [ ] Configure QoS on new office router (DSCP EF for voice)
- [ ] Disable SIP ALG on new office router
- [ ] Test jitter and packet loss during peak hours
- [ ] Set up voice VLAN if switch supports it
Week 3: Equipment
- [ ] Order desk phones for reception and shared spaces
- [ ] Deploy softphone apps on all laptops
- [ ] Deploy mobile apps for mobile workers
- [ ] Test every phone: inbound, outbound, transfer between offices
Week 4: Go Live
- [ ] Port local number to new office (if keeping existing number)
- [ ] Update auto-attendant: add new office as menu option
- [ ] Test inter-office transfers (office 1 → office 2)
- [ ] Verify caller ID shows correct office on outbound
- [ ] Quick reference cards at every desk
The Costs
| Approach | Setup Cost | Monthly (10 users) |
|---|---|---|
| Second PBX + PRI circuit | £15,000-25,000 | £1,200-2,000 |
| Extend cloud VoIP | £0-1,500 (phones only) | £240 |
Cloud VoIP second office: £240/month. Legacy second office: £1,200-2,000/month + £15,000 upfront. The decision is not close.
DialPhone makes multi-site expansion trivial. Add the new office in the admin portal, ship pre-configured phones, connect the same CRM integration. One system, one bill, one support team across all locations.
