Let’s see what it costs to add Direct Routing to your Teams installation and when it makes sense to use Calling Plans and when to use external Vendors.
Microsoft Licensing costs
Average savings via Alternative Vendors
Your monthly spend on inbound and outbound calls
Certified SBC costs
We assume that you already have Teams subscription with Phone System enabled. The cheapest is E1 + phone system add-on for $16/month
Calling plan add-on license is $12/month for Domestic (includes 3,000 minutes does not roll over)
or $24/month for Domestic + International ((includes 3,000 domestic minutes + 600 international,does not roll over)
or Usage based calling plan with auto-debit from your credit card on file. Official price list.
Microsoft Calling Plan
Calling Plans are not available in your country. List of just 13 countries where it is available.
You need to preserve existing PBX or ACD system for its unique functionality. Office365 PBX is quite basic.
You already have relations with SIP trunk provider and plan to continue use it. You just need a certified SBC to make a connection.
You are a heavy user of outbound and inbound calls so Savings will justify the extra cost and effort to configure Direct Routing
You have low usage per line and have over 30 lines so paying fixed fee for Calling Plans makes no sense