We use "Zadarma" ourselves and recommend it to our clients. For a reasonable price, you can set up quality call tracking. We haven't encountered any problems; everything works smoothly. The technical support quickly resolves any issues. In addition to landline numbers, mobile numbers are available with the ability to receive SMS, which can sometimes be necessary. I recommend it; it offers an excellent balance of price and quality. The only thing, in my opinion, is that the personal account could be made more user-friendly.
