I would not be confident, and would also like to know the real ICO adress.

Quick search by whois request on the quoted site domain "ico-telegram.com":

 Domain Name: ICO-TELEGRAM.COM
   Registry Domain ID: 2216022079_DOMAIN_COM-VRSN
   Registrar WHOIS Server: whois.namecheap.com
   Registrar URL: http://www.namecheap.com
   Updated Date: 2018-01-20T21:02:51Z
   Creation Date: 2018-01-20T20:48:25Z
   Registry Expiry Date: 2019-01-20T20:48:25Z
   Registrar: NameCheap Inc.
   Registrar IANA ID: 1068
   Registrar Abuse Contact Email: abuse@namecheap.com
   Registrar Abuse Contact Phone: +1.6613102107
   Domain Status: clientTransferProhibited https://icann.org/epp#clientTransferProhibited
   Name Server: DNS1.NAMECHEAPHOSTING.COM
   Name Server: DNS2.NAMECHEAPHOSTING.COM
   DNSSEC: unsigned
   URL of the ICANN Whois Inaccuracy Complaint Form: https://www.icann.org/wicf/
>>> Last update of whois database: 2018-02-19T13:14:33Z <<<

For more information on Whois status codes, please visit https://icann.org/epp


Telegram.org whois request by comparison

Domain Name: TELEGRAM.ORG
Registry Domain ID: D103450826-LROR
Registrar WHOIS Server: whois.godaddy.com
Registrar URL: http://www.godaddy.com
Updated Date: 2017-05-31T23:54:54Z
Creation Date: 2003-12-15T14:48:05Z
Registry Expiry Date: 2018-12-15T14:48:05Z
Registrar Registration Expiration Date:
Registrar: GoDaddy.com, LLC
Registrar IANA ID: 146
Registrar Abuse Contact Email: abuse@godaddy.com
Registrar Abuse Contact Phone: +1.4806242505
Reseller:
Domain Status: clientDeleteProhibited https://icann.org/epp#clientDeleteProhibited
Domain Status: clientRenewProhibited https://icann.org/epp#clientRenewProhibited
Domain Status: clientTransferProhibited https://icann.org/epp#clientTransferProhibited
Domain Status: clientUpdateProhibited https://icann.org/epp#clientUpdateProhibited
Registry Registrant ID: C136539947-LROR
Registrant Name: Registration Private
Registrant Organization: Domains By Proxy, LLC
Registrant Street: DomainsByProxy.com
Registrant Street: 14455 N. Hayden Road
Registrant City: Scottsdale
Registrant State/Province: Arizona
Registrant Postal Code: 85260
Registrant Country: US
Registrant Phone: +1.4806242599
Registrant Phone Ext:
Registrant Fax: +1.4806242598
Registrant Fax Ext:
Registrant Email: TELEGRAM.ORG@domainsbyproxy.com
Registry Admin ID: C136539948-LROR
Admin Name: Registration Private
Admin Organization: Domains By Proxy, LLC
Admin Street: DomainsByProxy.com
Admin Street: 14455 N. Hayden Road
Admin City: Scottsdale
Admin State/Province: Arizona
Admin Postal Code: 85260
Admin Country: US
Admin Phone: +1.4806242599
Admin Phone Ext:
Admin Fax: +1.4806242598
Admin Fax Ext:
Admin Email: TELEGRAM.ORG@domainsbyproxy.com
Registry Tech ID: C136539950-LROR
Tech Name: Registration Private
Tech Organization: Domains By Proxy, LLC
Tech Street: DomainsByProxy.com
Tech Street: 14455 N. Hayden Road
Tech City: Scottsdale
Tech State/Province: Arizona
Tech Postal Code: 85260
Tech Country: US
Tech Phone: +1.4806242599
Tech Phone Ext:
Tech Fax: +1.4806242598
Tech Fax Ext:
Tech Email: TELEGRAM.ORG@domainsbyproxy.com
Name Server: NS-CLOUD-B1.GOOGLEDOMAINS.COM
Name Server: NS-CLOUD-B2.GOOGLEDOMAINS.COM
Name Server: NS-CLOUD-B3.GOOGLEDOMAINS.COM
Name Server: NS-CLOUD-B4.GOOGLEDOMAINS.COM
DNSSEC: unsigned
URL of the ICANN Whois Inaccuracy Complaint Form: https://www.icann.org/wicf/
>>> Last update of WHOIS database: 2018-02-19T13:16:29Z <<<

The domains don't match, I doubt Telegram would take a risk on hosting it's ICO on another domain, despite DDOS risks.
Also the registar name of "ico-telegram.com" @ namecheaphosting is not very encouraging, the URL is ".com" whereas telegram is ".org"
All this point to a badly driven scam try.
Best regards :-)