I set up direct routing with our sip providers sbc. But didn't have a dial pad in Teams to make any test calls. After some research and convincing our Microsoft support provider of the licenses I need (that's a different story). I outlined you need 3 things to have a dial pad in Teams.
1. The user must have a voice license, like Phone System or Business Voice.
2. The user must have Enterprise Voice enabled. This is typically done in PowerShell using Set-CsUser.
3. The user must be "granted" a Voice Routing Policy.
The Phone system license will either be an add-on to our E3 license or will be apart of an E5 license.
If you are migrating from Skype for Business to Teams, Enterprise Voice should already be enabled.
You should have Voice Routing Policy set up for Teams and you will use the command Grant-CsOnlineVoiceRoutingPolicy -Identity username@domain.com -PolicyName "TeamsRoute".