Network Requirements
What your office network needs for WOCOM phones to work properly.
Most offices already have what they need. Run down the five points below — if all five are yes, your network is ready and you can stop reading. If one is a no, the step it points to tells you what to change. Whoever manages your network only needs the spec sheet.
Cat5e or better with RJ-45 ends. Anything installed in the last few years qualifies. → Step 1
Not a hub, and nothing older than 100 Mbps. A PoE switch also powers the phones, saving an adapter at every desk. → Step 1
You need to be able to prioritise voice traffic and turn SIP ALG off. → Step 2
Each call in progress uses 64 Kbps up and down. A 25-phone office needs about 1 Mbps of upload kept free. → Step 3
Speed matters less than steadiness. The four numbers below are what a call needs.
The Spec Sheet
Every value on one card. If you have an IT provider, this is the whole message to send them.
Outbound only. Nothing needs to be port-forwarded inbound.
UDP/TCP 5060 and 10000–20000UDP 19560–24560TCP 443TCP 80UDP 123 · UDP/TCP 53DSCP EF (46), highest priorityOffDurable, 30–60 s UDP timeout802.1Q, e.g. VLAN 10 (optional)64 Kbps per call, each way100 Mbps+, PoE preferredCat5e or better, RJ-45The path a call takes
Step 1 — Cabling & Switches
The physical side. Get this right and most call-quality problems never happen.
- Cat5e or Cat6 cable, RJ-45 both ends
- 100 Mbps or gigabit switch
- PoE switch (802.3af / at) so phones need no adapter
- A power outlet near the switch and the router
- Cat3 or telephone-grade cable
- Any hub, or a 10 Mbps switch
- Desk switches daisy-chained off each other
- Cable runs beyond 100 m without a switch in between
Sharing a switch with the PCs is fine for a small office. On larger sites, either give the phones their own switch or put them on their own VLAN, so a big file transfer cannot take the capacity a call is using. Both layouts are drawn in the reference section at the foot of this page.
Step 2 — Router Settings
Three settings. They are the difference between calls that sound right and calls that do not.
1. Prioritise voice
Put SIP and RTP above all other traffic, and reserve part of the upload for them. Without this, a backup or a large upload will break calls no matter how fast the connection is.
2. Turn SIP ALG off
It rewrites call setup messages it does not understand, and it is the most common single cause of one-way audio. Off unless WOCOM support tells you otherwise.
3. Let the ports out
Allow the outbound ports on the spec sheet. Nothing needs forwarding inwards — the phones connect out and the audio follows that path back.
Step 3 — Bandwidth
How much of your connection to keep free for calls. Find your office size and read across.
| Phones on site | Calls at once (typical) | Upload to keep free |
|---|---|---|
| Up to 10 | 3 | 0.5 Mbps |
| 10 – 25 | 6 | 1 Mbps |
| 25 – 50 | 13 | 1.5 Mbps |
| 50 – 100 | 25 | 2 Mbps |
These assume an average office where about one phone in four is on a call at the same time. For a call centre, where nearly everyone is on a call at once, double the figures in the last column. Download needs the same amount as upload, but upload is almost always the one that runs short.
Reference
The detail behind the three steps. Open only what you need — nothing here changes the checklist above.
Full port and firewall table
All outbound, from your LAN to the WOCOM platform. Nothing needs to be forwarded inbound.
| Service | Protocol / Port | Purpose |
|---|---|---|
| HTTP | TCP/80 | Phones collecting their configuration from WOCOM |
| TLS/SSL | TCP/443 | Encrypted SIP signalling |
| SIP | UDP/5060 TCP/5060 UDP/10000-20000 TCP/10000-20000 | Call setup between phones, the WOCOM platform and the gateways |
| RTP | UDP/19560-24560 | The audio itself |
| NTP | UDP/123 | Clock synchronisation |
| DNS | UDP/53 TCP/53 | Finding the WOCOM servers by name |
NAT behaviour
NAT maps your private addresses onto one public address. That mapping must be durable: each phone keeps the same external address and port while it is registered, with a UDP binding lifetime of 30–60 seconds. Without it, calls arrive with no audio or do not ring at all.
DHCP & DNS
Both are usually already correct — this is only worth reading if phones are not registering.
- DHCP must give each phone an IP address and mask, a default gateway and a DNS server
- Custom options such as Option 66 are not required, and are ignored if present
- Make sure the DHCP pool is large enough for the phones as well as the computers
- DNS must resolve external names, and a secondary DNS keeps registration alive if one fails
Network layouts — shared or separate VLANs
Small office — one network for everything
Around ten phones and computers together on a single untagged network. Simplest to build and to support.
Larger site — voice and data separated
What WOCOM recommends once a site outgrows a single switch. Each side gets its own addresses and its own QoS policy, and a fault on one side is far easier to isolate.
Switch port settings for the VLAN layout
| Port | Connected | PVID | Tagging |
|---|---|---|---|
| 1–8 | IP phones | 10 | Untagged 10 |
| 9–20 | PCs | 20 | Untagged 20 |
| 21–22 | Phone with PC behind it | 20 | Tagged 10, untagged 20 |
| 24 | Uplink to router | 1 | Tagged 10 + 20 |
Working the bandwidth out yourself
The table in Step 3 comes from two lines of arithmetic. Use these if your site does not look like an average office, or to check what an existing connection can carry.
- Calls at once = phones ÷ 4 (call centre: phones ÷ 2)
- Bandwidth needed = calls at once × 64 Kbps, each direction
- Calls a link can carry = bandwidth you reserve for voice ÷ 64 Kbps
What an existing connection can carry
| Upload speed | Reserved for voice | Calls at once | Phones (4:1) |
|---|---|---|---|
| 2 Mbps | 1 Mbps | 15 | 60 |
| 5 Mbps | 2.5 Mbps | 39 | 156 |
| 10 Mbps | 5 Mbps | 78 | 312 |
| 20 Mbps | 10 Mbps | 156 | 624 |
LAN capacity is rarely the constraint: meet the Step 1 requirements — 100 Mbps or better switching, Cat5e or better cable — and the office network will carry far more than the internet connection can.
Compatible phones & devices
WOCOM normally supplies the handsets. You may use your own if they are on this list — ask your account team to confirm a specific model before buying anything.
Polycom VVX
- VVX 101 / 201
- VVX 300, 301, 310, 311
- VVX 400, 401, 410, 411
- VVX 500, 501
- VVX 600, 601
- VVX 1500
Grandstream GXP
- GXP1600 series
- GXP1700 series
- GXP2100 series
- GXP2100EXT module
Grandstream GRP
- GRP2612, 2613, 2614, 2615
- GRP2712, 2713, 2714, 2715
Grandstream GXV video
- GXV3240 / GXV3275
- GXV3370 / GXV3380
Other brands
- Yealink
- Cisco / Linksys SPA 50x, 122, 30x
- Fanvil
- Htek
- Snom
- Zoiper (softphone)
What the terms mean
- SIP — the language phones use to set up and end a call.
- RTP — the audio itself, once the call is up.
- SIP ALG — a router feature that tries to help with SIP and usually breaks it. Turn it off.
- QoS — telling the router which traffic goes first. Voice goes first.
- DSCP EF (46) — the label voice packets carry so equipment along the way knows to prioritise them.
- NAT — how one public internet address is shared by everything in the office.
- VLAN — splitting one physical switch into separate logical networks, e.g. phones apart from computers.
- PoE — power delivered down the network cable, so a phone needs no power adapter.
- Jitter — variation in arrival time between packets. High jitter sounds like choppy or robotic audio.
- Latency — one-way delay. High latency makes both people talk over each other.
Rather have us check it? Send the
spec sheet to whoever manages your network, or send us a screenshot of your router settings and we will review them
before install day.
cloudsupport@wocomja.com