A cloud PBX handles your calls inside the company: extensions, queues, the IVR, the Linkus apps. To reach anyone outside, it needs a SIP trunk: a phone line over the internet, with your phone numbers on it. If your team is in Germany, the trunk usually comes from a German provider, and a few German rules decide which numbers you can get and how calls must look. (New to the term? Start with what a SIP trunk is.)
What a German SIP trunk gives your PBX
A trunk provides three things:
- Numbers. Single numbers, or a block of numbers with direct dial-in (in German offers often called Anlagenanschluss with Durchwahl), so every extension can have its own direct number.
- Channels. How many calls can go through the trunk at the same time.
- The way out. Outgoing calls to landlines, mobiles and abroad, and the routing of emergency calls to 110 and 112.
The PBX holds your users and call flows. The trunk is the bridge to everyone else.
Local numbers and the Ortsnetz rule
German geographic numbers (Ortsnetzrufnummern, the ones starting with a local area code such as 030 or 089) belong to a local area. The Bundesnetzagentur (BNetzA) sets the rules, and when a provider hands such a number to a customer, it has to respect that local link. The BNetzA's allocation rules look at where your home or business seat is, and numbers handed out against the rules must be switched off.
In practice:
- Expect your provider to ask for an address in the local area, sometimes with a document as proof.
- Moving to another city? A local number may not move with you.
- Want one number for the whole country? Germany has (0)32 national numbers with no local link. Some callers find them less familiar than a local area code, so think about who calls you.
Keeping your number: porting in Germany
You can take your existing number with you to a new provider, from ISDN, analogue or another VoIP line. German law (§ 59 TKG) sets the key rules:
- Your number is switched over on the agreed day, and at the latest on the following working day.
- When you switch provider, your service may not be down for more than one working day. If it is, the old provider owes you compensation for each extra day.
- The BNetzA makes sure you pay no direct fee for porting itself.
- You can still ask to port up to one month after your old contract ends.
You start the port with the new provider, not the old one. Local numbers stay in their local area. Our guide to porting a business number walks through the steps.
Caller ID: what your PBX may send
German law is strict about the number your calls show. Under § 120 TKG:
- An outgoing call must carry a complete German number that is assigned to you for that service.
- You may send an extra number (for example your head-office number, or a mobile number, a feature often sold as CLIP no screening) only if you have the right to use it, and it must be a German number.
- If a call showing a German number reaches the German network from abroad, the number is suppressed (roaming mobiles excepted).
What this means for you: send your German numbers through a trunk that hands calls into the German network, normally a German provider. A cheap foreign trunk that shows your German number may reach your customers as "number withheld". This is a summary, not legal advice. If caller ID matters to your business, check the details with your provider.
A checklist before you sign
| Check | Why it matters |
|---|---|
| Channels | Enough for your busiest hour. On PBXfactory the number of seats also sets how many calls your PBX runs at once, so match the two. |
| Numbers | Single numbers or a block with direct dial-in, in the local area you need. |
| Porting | Can they port your current numbers, and do they handle it for you? |
| Emergency calls | How 110 and 112 calls are routed and which address is registered for your site. |
| Codecs | G.711 A-law is the European standard. Ask what else they support. |
| Sign-in method | Registration with username and password, or IP-based. Both work with Yeastar. |
| Contract | Notice period, minimum term, price per channel or per minute. |
| Support | Opening hours, language, and how fast they act on outages. |
Providers on Yeastar's certified list
Yeastar keeps a list of SIP trunk providers it has tested in Germany. Check the product column. Not every entry was tested with P-Series Cloud Edition, which is what you run on PBXfactory. Providers tested with it, such as DIDWW, come with a ready-made template in the PBX, so you fill in your account details and most of the settings are already right. A provider that isn't on the list can still work over standard SIP. It just means more settings to enter yourself.
On PBXfactory
We don't sell SIP trunks or numbers. You pick the provider that suits you and add the trunk in your PBX's admin panel. Porting runs through that provider. Setting up trunks is part of configuring your PBX, so it isn't in our included support. Yeastar's documentation covers it, and if you'd rather not do it yourself, our Setup Assist package does it with you.