Issues with Dialing Internal Twilio Clients

[patrickappelman]

I have two accounts—one is able to dial other internal Twilio client numbers and one is not.

Case 1: Working Internal Call - John Calls Roger
A task is created with the following attributes and assigned to the current worker.

{
	"internal":"true",
	"name":"client:john",
	"autoAnswer":"true",
	"from":"John",
	"to":"client:john",
	"targetWorker":"client:roger",
	"url":"https://runtime-domain",
	"worker_call_sid":"CAfccbc6b114e52f7704924772c8b02b5d",
	"direction":"outbound"
}

Another task is created, reserving the recipient client, with the following attributes:

{
	"internal":"true",
	"name":"John",
	"autoAnswer":"false",
	"from":"+18448144627",
	"to":"client:john",
	"targetWorker":"client:john",
	"conferenceSid":"WT39224f8996e032d1cfcdd148bc36a95c",
	"direction":"outbound"
}

Case 2: Non-Working Internal Call - Roger Calls John
A task is created with the following attributes and assigned to the current worker.

{
	"internal":"true",
	"name":"client:roger",
	"autoAnswer":"true",
	"from":"Roger",
	"to":"client:roger",
	"targetWorker":"client:john",
	"url":"https:\/\/runtime-domain",
	"direction":"outbound"
}

No reservation task is created.

For Case 2, I receive the following error in Debugger:

Error - 40113
Error Making Outgoing Call - Call Instruction
The call instruction encountered an error when requesting an outgoing call be made from the API. Code: [21212] - From is not a valid phone number: Roger - ReservationSid: WRd438f23011207f9926e5966c4d4c2e0b

{
    "message": "From is not a valid phone number: Roger",
    "code": 21212,
    "user_error": false,
    "http_status_code": -1,
    "params": {}
}

Any idea why one account would be able to call internally but the other account cannot?