Connect VoIP.ms SIP trunk to SessionPBX

VoIP.ms supplies US, Canadian and international numbers (DIDs) and outbound calling. VoIP.ms can send a number’s calls to a SIP address, and authenticates outbound calls from a sub account with a username and password. In SessionPBX you add two trunks: one that receives VoIP.ms’s calls and one that sends your outbound calls.

You bring your own VoIP.ms account, numbers and caller ID. SessionPBX doesn’t supply VoIP.ms service.

About this guide. The VoIP.ms settings on this page were checked against VoIP.ms’s published documentation on 19 October 2026. The SessionPBX field names come from the Add SIP trunk wizard in the product. If VoIP.ms shows a different value in your account, use theirs.

Before you start

1. Pick the VoIP.ms server nearest your SessionPBX region, and use it for both your numbers and your sub account. For example:

   SessionPBX region	VoIP.ms server	IP address
   London	london1.voip.ms	208.100.60.34
   New York	newyork.voip.ms	208.100.60.66

   Check the current address for your server on VoIP.ms’s Servers page.

2. Create a sub account for SessionPBX with username and password authentication. Note its username (your account number, an underscore and the sub account name) and password.

3. Set the sub account’s caller ID to one of your VoIP.ms numbers.

SessionPBX addresses for VoIP.ms

Give VoIP.ms the address for the region your workspace is hosted in. If you’re not sure which region that is, email support@sessiontalk.co.uk.

SessionPBX accepts calls from carriers on UDP port 5060 or TLS port 5061. TCP isn’t accepted for incoming calls. Calls that SessionPBX sends to VoIP.ms can use UDP, TCP or TLS on whatever port VoIP.ms specifies.

Part 1: Inbound calls

In VoIP.ms: send your numbers to SessionPBX

1. Open DID Numbers > Manage DIDs and edit the number.
2. Set its Point of Presence to the server you chose.
3. Under routing, choose SIP URI and create a new SIP URI using the {DID} tag, so one URI works for every number. Put the country code in front if VoIP.ms lists the number without it, for example 1{DID}@us.sip.sessiontalk.io for US and Canadian numbers.
4. When you create the SIP URI, turn on CallerID E164 so callers’ numbers arrive in international format.
5. Repeat for each number.

In SessionPBX: add the inbound trunk

1. Open the SessionPBX project, select Call Routing, and on SIP trunks select Add trunk.
2. Provider: name it VoIP.ms inbound and choose Generic carrier (IP authentication).
3. Connection: set Host to your VoIP.ms server, for example london1.voip.ms, Port to 5060 and Transport to UDP. Set Direction to Inbound only.
4. Authentication: keep By our IP address. Under Carrier IP addresses, enter your VoIP.ms server’s IP address, for example 208.100.60.34.
5. Inbound: list your VoIP.ms numbers in international format, for example +15145550100. List your numbers on this inbound trunk only. Don’t add them to the outbound trunk: a number listed on two trunks belongs only to the trunk saved last.
6. Select Create trunk.

Part 2: Outbound calls

1. On SIP trunks, select Add trunk again.
2. Provider: name it VoIP.ms outbound and choose Generic carrier (username and password).
3. Connection: set Host to the same VoIP.ms server, Port to 5060 and Transport to UDP. Set Direction to Outbound only.
4. Authentication: choose Username and password and enter the sub account’s username and password. Leave Auth realm and From domain blank.
5. Turn Register to this carrier off. Your incoming calls arrive on the inbound trunk instead. Register to this carrier is on by default for Username and password, so check that it shows off before you continue. Leave Inbound numbers empty on this trunk. Your numbers belong on the inbound trunk only.
6. Outbound: set Caller ID to one of your VoIP.ms numbers.
7. Select Create trunk.

Route your numbers

On Call Routing, use Inbound number routing to choose where each number rings: everyone, a team member, a ring group, a call queue or a call flow. See Phone Numbers & Outbound Calls.

Allow members to call out

Outbound calling is off for new members. Open Team Members, edit the member, turn on Outbound PSTN under Access & features, and select Save member.

Members can dial numbers in international format, such as +447700900123. SessionPBX sends the number to VoIP.ms in international format.

Test the trunk

1. Call one of your VoIP.ms numbers from an outside phone and check that the right destination rings.
2. With Outbound PSTN on for one member, call a public number. Check that audio works both ways and that the called phone shows the caller ID you expect.
3. If you call into an IVR, check that key presses work. SessionPBX sends and receives key presses as RFC 2833 telephone events.

If calls fail, email support@sessiontalk.co.uk with the time of the call, the number you called from and the number you called.

Sources

• VoIP.ms: SIP URI 
• VoIP.ms: Servers 
• VoIP.ms: Sub Accounts 
• VoIP.ms: Manage DID