You might try and see if you can port the 877# to VOIP.ms (VOIP.ms is great for lower volume PAYGO virtual PBX management as you can do everything you're after, including IVR, voicemail transcription, fail-over, and availability times with them), or use a virtual 800# host like Avoxi to forward to other phone numbers (potentially great for rerouting during infrastructure outages to alternate working numbers as long as
their exchange routing isn't hosed as well) like one hosted at VOIP.ms. Unfortunately, your question and my answer is going to introduce an awkward discussion about telephone infrastructure, redundancy, service outages, and security to help you understand any negative reviews you might find from last month during your own research.
VOIP.ms went through the wringer last month with a brutal DDoS for ransom attack (
$4m+ in buttcoin was demanded, for the record - screw crypto currencies for enabling this sort of garbage) that lasted two weeks before they could mitigate it enough to restore connectivity to customers with the help of Cloudflare, and the instant they did, the attackers hammered Bandwidth.com, a top-level CLEC and one of the CLECs VOIP.ms trunks with, who themselves were so overwhelmed that it took a week of reduced quality and switching to Cloudflare as well themselves... yielding nearly a month of none to spotty service for VOIP.ms customers... ourselves included. It wasn't a fun time.
The important thing is, nobody is immune to this sort of thing anymore given
all telephony is technically some form of VoIP service now, they didn't cave to the absurd ransom demands, and they restored service. Communication wasn't great, but understandable under the circumstances. And the yahoos doing this have been randomly bringing to bear on a whole slew of VoIP providers the past few months, and may or may not be the same outfit that did the Colonial Pipeline hack a few months back.
The Bandwidth.com DDoS attacks peaked at 130 Gbps and 17.4M pps across network layers 3, 4 and 7... which is absolutely bonkers.The only mitigation to potentially avoid downtime in this day and age is using redundancy and flexibility with multiple providers who don't share the same backbone providers, which is difficult given how incestuous the telecom industry is. It requires you to have fallback service options and keep info on hand to port your number in and out of providers if necessary. The Bandwidth.com attacks had knock-on effects that even spilled over and impacted quality of service with massive business VoIP providers like 8x8 and RingCentral, cable phone providers like Charter and Cox, healthcare/hospital communications networks and some Fortune 500 call centers, conference platforms like Zoom and MS Teams, a Canadian cellphone provider who's name I can't recall off the top of my head currently, Google Voice and Republic Wireless were directly impacted, and even some spillover was experienced with some Verizon customers during that week with call quality and reliability. These two threads over at DSLReports are enlightening, horrifying, entertaining, and frustrating to read as a crash course on how miserable it is to try and route around these sorts of attacks:
https://www.dslreports.com/forum/r33210774-Voip-ms-VOIP-MS-may-have-an-outage-right-nowhttps://www.dslreports.com/forum/r33218866-Apparent-attack-on-Bandwidth-com-25-September-2021