The honest version first
This is the closest comparison on this site and we are not going to pretend otherwise. Quo is well built. The trial lengths are the same, seven days each. The prices are within a few dollars. If what you need is a shared business number with good texting for a small team, Quo does that well and you will not be unhappy.
The question is what happens as you grow past that, and whether you are running one business or several.
How they compare
Compared against Quo's published pricing, 22 October 2026.
| SoundLine | Quo, formerly OpenPhone | |
|---|---|---|
| Entry price | $19.99 per user monthly, $14.99 annual | $19 per user monthly, $15 annual |
| Mid tier | $33.33 per user monthly, $24.99 annual | $33 per user monthly, $23 annual |
| Free trial | 7 days | 7 days |
| Numbers included | One local number on the trial, additional $4 on Growth | One local or toll-free per user, additional $5 |
| Desk phone support | Yes, provisioned on Growth | App first |
| Call routing and IVR | Advanced IVR on Growth | Simpler routing |
| Several businesses | Designed for it: a separate account per business, one login | One workspace |
| Phone support with a person | Included on Growth, US-based | Support channels vary by plan |
| Operating the network since | 2008 | Founded 2018 |
Three things that decide it
You run more than one business. This is the real dividing line. If you have two companies, or three, every one of them needs a number, a greeting, and somewhere to ring. SoundLine keeps each one in its own account, reached from one login and one app, so you know which business a call is for before you answer it. That is the product's organizing idea rather than a feature bolted on.
You have, or will have, desk phones. Not every business is app-only. Front desks, warehouses, exam rooms and shop counters still want a handset on the wall. SoundLine provisions them. If you will never own a desk phone, this difference costs you nothing.
You want a phone number to call when something breaks. Growth includes US-based phone support. When your phone system is the thing that is broken, email support is an uncomfortable place to be.
When Quo is the better choice
If you are a solo founder or a small team who needs one shared business number with excellent texting, and you have no interest in desk phones, call routing or running separate identities for separate companies, Quo is simpler and will suit you better. Simplicity is a real feature and we are not going to argue against it.
Note also that the product is mid-rebrand from OpenPhone to Quo, so you will meet both names for a while. That is a cosmetic issue, not a reason to choose or avoid them.
Try it against what you have
Seven days, your own number, your own calls. Keep your Quo account running alongside it. If SoundLine does not earn the switch, cancel in two clicks and nothing is charged.